I really apologize if there's a better place to post this, I really couldn't find somewhere I thought this would fit into better. :/ I found a sims 3 full face makeup that I want in my sims 2 game, but I'm not sure how to go about it or if it is is possible/extremely difficult. Any help is greatly appreciated!

It's certainly doable, but you have to remember that TS3 textures are all greyscale - they have no colour. The simplest option would probably be to open the TS3 file in S3PE and extract the texture. Copy the alpha channel of the texture, and use that as the alpha for your TS2 makeup, and then create the main texture (with colours) by hand. If that's too much work , you can always try importing the TS3 makeup into TSRW, setting the colours you want there, and then using the 'Export complate' feature (the location of which I have temporarily forgotten)... to export a single, coloured texture, which you can then split into an alpha and a main texture for use in Bodyshop.