The map is a bsp file, but you won't be able to decompile it through VMEX because it isn't a half-life 2 map. The only option you have is to email the map author and ask them for the uncompiled map files. The game is based Quake engine, so if you can get the map file, you should be able to open it in Quark or Hammer or something. Then you would probably need to re-texture it, delete the entities that Torque doesn't use (you don't need flag capture zones or spawn points), and then export it. This won't get the custom models though, you'll need to export them all in .dts format too.
Short answer: No.
