Moving away from XCode to GCC on OS X

I have a code base that I build on Snow Leopard, XCode 3.2.6 and targeting the 10.5 SDK 32/64bit, INTEL only. Works fine. I do this in a virtual machine.

Now I have GCC 4.7.1 compiled and working on Mountain Lion, XCode 4.4 tools installed so that I can have all the necessary libraries, dependencies.

I'd like to move away from XCode to GCC targeting the 10.5 SDK still or even the 10.6 SDK would be fine.

Do I have to create a MakeFile? Is there someway to export one from XCode? I dont know a lot about creating a MakeFile from scratch.

I know that I can append -mmacosx-version-min=10.5 to the gcc command and that I have to tell it 64-bit as well.