If you don't want to compile yourself: Read the
Wine installation page for Mac OS X, especially the section about prebuilt binaries. Maybe one of the third-party projects listed there suits your needs. Consider reading ccx's link before deciding to use Wine-based third-party packages, it doesn't seem that hard to follow.
If you search the web for "wine mac easy", you'll retrieve a video which I didn't watch, but a ton of people commented with "thank you".
The forum talk is mainly about challenges right now, which is healthy. I feared the multiplayer stuff would have torn the community apart, since it's not something for everyone, and also not Lemmings; but it hasn't. Level building isn't popular currently, but that would also be Lemmix-replay-centric. There's the occasional fan corner topic, but it's hard to make a fresh fan topic interesting enough to spawn several answers. Small talk usually happens via IRC (geoo: "It appears that my new neighbor is called P. Wurst"), very little smalltalk reaches the forums, especially since the rabble box is gone.
There are also less programming projects discussed in the forums than a few years ago. The major editors aren't hacked on (Lemmix, Lemmix 2 due to lack of time, lgl2, pcL2ed, and Mindless's L3 editor). The file formats of most games are figured out, and several functional resource extractors have been written. Lix is nearly IRC-only.
-- Simon