OSX custom compile help

I am rather new at compiling from source and have questions about a custom configuration I want to attempt. I have compiled libogg, libvorbis to usr/local/lib and and vorbis-tools to usr/local/bin. I have both the Xiph oggenc and the aoTuV b5 oggenc2. Everything works. I would like to compile Audacity with Ogg suppport, but to use use the external aoTuv encoder. I have the 1.3.5 source tar, and have read the configure --help and see that some manner of setting ./configure options should handle something like this, but there I get confused.
First, am I on course in assuming that I can build this proj to utilize pre-compiled libs and binaries? ( By pointing to the external directories?) Or will it build with those versions included and thus be portable but not adaptable to external changes. Either way is fine, I just want to understand how the dependencies work. Static, shared, dynamic,system vs local, linked libs and such are still a bit fuzzy.
So what sort of command line need I construct to configure? Do I want the tar pkg or SVN source? Leave my local versions where they are or add their sources to the compile folder? Do I need to change ENV vars like $Path or ldflags ? Syntax and usage of Prefix= is also not clear to me. In short, anything but a standard default ./configure, make, make install is not quite my league yet, at least for anything more than simple options.
I think I can handle getting wxMac set up first, though I probably should try a default install for practice.
This will be on OSX 10.5.1 on 1GHz iBook PPC, in Terminal.
Thanks, Josh