We use Cineform here all the time.
Another good choice would be DNxHD, but I like Cineform better.
Neither is truly lossless, but they are close enough for most workflows.
Thanks. Now I just need to figure out what the methodology is to actually adding the codec to AE.
Once it's installed on the system, it should be visible in AE. Choose AVI format (or MOV) and for the codec, choose Cineform.
Look for it with the name "GoPro-CineForm Codec".