I really can’t do much more than recommend this quick how-to, and point out that I entirely agree.
I dearly love time machine, and it has its place, but when it comes to tracking changes in anything more complex than a couple dozen lines of code, or more importantly, figuring out what changes you made and why, nothing beats having the convenient log of what you did and why that version control provides. The recommended gitX makes it pretty easy, though I find the branch merging to be a bit lacking (I prefer to use Tower).