A couple of tips to get it running: the mod ships with a bunch of resolution-specific executables in the main folder. Launch the one with the resolution you want. Before you launch, right click on it and set the compatibility to Windows XP Service Pack 2. Note that the in-game graphics scale to whatever resolution you ran, but the menu and pre-mission screens do not, being static pixel images. The game looks and plays best in the 12xx by 7xx range, IMHO.
Pro tip to those who haven't played it in years: on mission 3, you are ambushed by a Mad Cat. Send a disposable mech and greenie merc over the bridge just south of the start zone (before it's destroyed a few seconds into the mission) and fight your way south to the mad cat, which will squash you like a gnat, but also be visible. Then just use a big and little artillery strike on it (may take several tries) and the pilot will eject, leaving you with a mech that will save your ass over the next 10 missions or so.