Get RAPE 2, take the MW2_Modder.dll file and the ini file and copy it to your MW2 folder. Open the ini configuration file and edit the "Mod0=RAPE2" line on the bottom to Mod0=*the exact name of the folder with the mod inside your MW2 folder*
The folder from what I've seen is ?????/maps/mp/gametypes/.gsc file
While running MW2, use Winject to inject MW2_Modder.dll into MW2.