Ah - that would explain why its not in the MIDI pack. I didn't write the techno-based music. I did all the orchestral stuff (mission music, cutscenes, ect). Daniel Brito is the composer of the techno tracks found in the simulator (we did use the UE theme for one of the sim missions, and a few renderings of WC1 music in some of the other sim missions). The MIDI pack was something I put together post-release of the orchestral music. I don't know if Daniel worked with MIDIs along the way with his writing or not, so I couldn't really include them.
Probably the easiest way to get this mp3 would be to extract it from the tre file or use HCl's converter. Unfortionately I can't guide you with that. I write the music - I don't deal with the computer stuff
I'm glad you enjoyed the music in UE. I don't know if you have, but checkout Standoff. I'm doing all the jazz arrangements, original orchestral music, and WC2 (and other) renders, with Daniel doing techno music for the simulator again, so it's more of the same.