Trigger Maru and Operation Monsun are completely different concepts. They may share a few files, but they have a great many more which will override each other. The best thing to do is get MultiSH4 and create different installations, one for each.
Original
http://www.subsim.com/radioroom/down...do=file&id=433
UBM 1.5
http://www.subsim.com/radioroom/down...o=file&id=1110