Problem with mdl export

I’ve been browsing this forum for a while ,mostly for the tutorials, but i encountered a problem and i hope someone can help me.
I’ve been exporting models to .3ds since i started, and then using custom scripts to load it into c++, but now i need to export models into .mdl and i’ve been having a lot of problems finding an addon for that. I tried ajmdl_export_055 but can’t load it properly into blender. Placing it on the addon folder does not work, trying to install it from another folder does not work either, it simply won’t show on the addon list. I even tried to “trick” blender by changing the header of the python script to say it is for 2.6. Currently i have Blender 2.6, but have no problems downgrading if needed.
Does anyone know of a script that allows export to mdl and works with 2.6?