Hmm that's a different way, I suppose I can try that. Previously when using things like Hexxit you would download Optifine, extract the files, open the modpack.rar with 7zip (or whatever you may use to open such things), and then drag the contents of Optifine putting it directly into the modpack.rar and just launch the game like normal. I was thinking since it didn't work the same with Attack of the B-Team, after I downloaded Optifine for 1.6.4 and followed my previous steps, that maybe some of the mods didn't support Optifine since I know there are some that don't.
Edit: Upon trying the way you instructed opening Optifine on my desktop, I'm only given the option of installing it into vanilla Minecraft and I'm unable to "write the technic (%appdata%) URL".