You've been busy with the Incredible Machine games recently. I really enjoyed them when I was young, too.
I just saw that you uploaded the CD soundtrack for 3 (and gave you your first download). Nice work. There's a problem, though: _inmm.dll throws up an error about missing registry information and tells me to run _inmmcnf.exe. Once I run _inmmcnf.exe and simply exit, I can then run the game without error and the soundtrack works. So, it's adding registry information on first run. It looks like you probably need to edit your instructions to tell the user to run and close _inmmconf.exe once before starting the game.
Other than that, it works great. Good job. I might care to do something similar with _inmm.dll in the future. It's not as elegant of a solution as the winmm.dll that some games (like Jedi Knight) use, but it's probably a lot easier to adapt and configure for any game.
BTW, I found that the music still works if you move the MP3s to a folder named Music and then add "Music\" before each filename in _inmm.ini. I like that because it makes things a little neater, IMO.
Oh, if I may make a friendly suggestion: if you use zip format, then the few people who don't have 7zip or WinRAR installed will still be able to open it. It won't be any larger, since the contents are already compressed. There's really no benefit to using 7zip in this case, just potential frustration for some users.