When I go into user preferences>addons>install from file, I install the blender_source_tools2.5.2.zip and it shows up in the list of installed addons, but I cannot use any of it's functions. I am currently using blender 2.7.4. No error messages, I just do not have the import/export "studiomdl Data" option, or the interface that is supposed to be added to the menu on the right... also, the folder in the zip is called io_scene_valvesource instead of the io_smd_tools python script file I see in this tutorial: HellJumper's Blender 2.5 Modeling Tutorial for TF2
however, I used this vid to actually try to install blender source tools
SFM - Installing Blender Source Tools(2.74)