1) Modding AIM, what's that?
To "mod" AIM is to edit some key files using a resource hacker and/or a hex editor, changing the look of your client. You can create a more personalized AIM.

2) What files need to be edited?
The most common file to edit is AimRes.dll, which is located in your AIM directory--usually C:\Program Files\AIM or C:\Program Files\AIM95. There are two other files in that same directory that are commonly edited as well--buddyui.ocm and icbmui.ocm.

3) What can I do with AimRes.dll?
AimRes.dll contains nearly everything visually related to AIM. If you wanted to, you could make your AIM look as plain and dull as bread, or as animated and annoying as a class of pre-schoolers.

Personally, I don't prefer the minimalist look, so I'm not very experienced with it. The things I change are little nuisances such as removing a few buttons on the bottom of the buddy list, changing the window text on the top of the buddylist to display only my screen name, rather than "'s Buddy List Window" and some other random things.

4) What can I do with buddyui.ocm and icbmui.ocm?
These are usually edited to change only certain colors of text and backgrounds within the buddylist and IM/Chat windows. I only use these two to change some specific colors within AIM, though other modders out there use these to further customize their AIM beyond coloring.

5) How do I edit AimRes.dll?
The most popular way of doing this is by using Resource Hacker. Just unzip, run ResHacker.exe and open up your AimRes.dll (from your AIM directory) and you'll see just about everything visually related to AIM--images, text and instructions on how AIM is supposed to look.

Here's a simple one to try out- change the yellow "away" notepad to a different color. I use a simple blue one I edited from the original- http://jon8rfc.homeip.net/aim/bitmaps/away_blue2.bmp ; save this image to your desktop. Navigate your way in AimRes.dll to Bitmap 200, right-click on 1033 within the 200 folder, click on the fourth menu item "Replace Resource...". Open up the location of the notepad you saved from my site, replace and save.

6) How do I change colors in buddyui.ocm and icbmui.ocm?
You'll need a hex editor to edit these two files. I prefer to use HexEdit v1.03. This is a standalone .exe with no fancy features. One very handy thing is that HexEdit v1.03 does not actually open the file you want to edit; the file's contents are merely copied into HexEdit. By doing this, you can leave the window open where you were last editing and run AIM, without AIM stating that their file "is in use", forcing you to lose your place where you were editing.

7) What is all this garbage I see in HexEdit?
On the left are hex offsets (locations) and in the middle are the hex values, and to the right are ASCII values. In the middle section (hex values) you will see 16 pairs, and each pair is one offset. On the far right, the ASCII values are directly proportionate to the hex values (changing when you modify the hex values and vice versa), but not visually necessary for changing colors.

"Hex counting", as I like to call it, is the ascending order in which hex values are ordered. Starting with zero, you count up to nine, then move to the letter A and count up to F- 0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f

It is important to know the order of hex values, because you'll need to find the exact location (the offset) of what you want to edit. Keep in mind that no other alphanumeric characters exist as hex values apart from the 16 I've listed.

8) So I can "hex count"...now what?
Now all you have to do is know the hex offset for what you want to change. If the offset you're looking for is "645D", start scrolling down and watching the left hand side until you see "6450"...you are now on the correct row. The offset you need to locate is 645D, so starting to the right of "6450", count over 14 pairs starting with zero, up to D (0,1,2,3,4,5,6,7,8,9,a,b,c,d)--the easier way is to count backwards from the right at 645F (the farthest right pair) back 3 pairs to 645D (f,e,d).

The offset is 645D, but because you started counting pairs with ZERO rather than ONE, you will be 14 pairs over instead of just 13 (0,1,2,3,4,5,6,7,8,9,a,b,c,d), and if you started at the right side, you will be over to the left 3 pairs (f,e,d).

9) How many hex values (or pairs) do I need to change for each color?
A standard hex color code is made up of 6 values (3 pairs) total. For example, absolute black is "00 00 00" and absolute white is "FF FF FF". One thing to note is that AIM, for some odd reason, doesn't always accept "00 00 00" as black, so just use "01 01 01" and you'll be fine.

645D is the offset for 5.5.3415 buttons background color. If you navigate to offset 645D, you will change three consecutive pairs, starting with 645D; change 645D, 645E and 645F (the last 3 pairs on the 6450 row). If you want the buttons background color to be blue, change "FF FB F0" to "00 00 FF".

10) My buddylist background color isn't showing, what's the deal?
For the buddylist background color to display, you must delete Bitmap 273 from AimRes.dll. Open up AimRes.dll with ResHacker and navigate your way to BITMAP>273. Click on the "1033" located within the 273 folder. You will receive an error stating "Access violation" which is perfectly normal when using ResHacker. Just click OK on that window, right-click on 1033, click on the next to last menu item of "Delete Resource [Bitmap : 273 : 1033]" and save your AimRes.dll.

Run AIM and you should no longer see the old AOL/AIM background image. If you've already changed the background color in buddyui.ocm, you should now be seeing your set color.