Just thought I'd mention that I have the 360 version, and it appears its Monkey1.pak is somehow formatted differently to the PC version. Here are the size and checksum specs:
204 MB (214,930,550 bytes)
I've tried using both extractpak and Remonkeyed Explorer on this file to no avail (the former just crashes, and the latter claims that the format isn't supported or something along those lines). What are the chances of support for this version being added in future? I don't know if it has anything to do with how I got the .pak file extracted (I first backed up my MI:SE download onto a USB stick, then used wxPirs on the one file created to read its file system and rip the .pak out).