Tutorial on porting and hexing models

Can anyone give me a tutorial on how to port and hex models from video games to gmod. What programs would I need. Do I need multiple programs for certain games? I feel it will be a lot more convenient if I can port my own models than depending on others. Also might make some releases of my own. Any help would be appreciated. Thanks.

http://www.facepunch.com/showthread.php?t=534654&highlight=hexing+tutorial
For hexing, and for porting… I don’t know.