Ok... I've struggled enough with trying to make a custom model, and I tried to teach myself, but I'm stuck. This is what I've done. I made a model and textured it in Softimage, and exported the 3 SMD files that I need to export. Now because all the tutorials are old and are for orangebox and stuff, I can't figure out what to do. I tried making the qc file and dropping it onto the studiomdl in common>portal 2>bin, but I guess I'm typing it wrong and I can't exactly figure out how to write it correctly. I placed the 3 SMD files and the QC file in my portal 2>portal2>models>modelname folder that i created. I could really use some help here. I was following this guide
EDIT
I FINALLY GOT IT TO WORK! so so tired... must sleep .
If anyone else is having compiling problems. THIS was a great link. Just skip all the Maya talk, if your not using Maya.

This was made by a classmate of mine to try to help me out with a custom player character model import issue for portal2. An issue I'm still sadly having BUT I'm glad it helped you!

Next time I see him I'll give him a thumbs up for you.