[OS X TeX] Single-stepping through TeX

[Doug McKenna]

Is there any way to single-step through a very simple TeX execution 
(after inputing the plain format), in order to watch with a debugger how 
it operates?  Preferably using the XCode environment that in turn depends 
on gdb.

I've got TeXLive 2010 installed, with the 2011 disk available.

Although there's a directory in the distribution tree for web2c, I can't 
find any executables or sources or directions that make it easy (no doubt 
for some value of "easy") to convert TeX's source code into final 
runnable C code for the command line program "tex".

Searching the web hasn't helped much either, except to make clear that 
the endeavor looks completely frought and complex.

Thanks.

Doug McKenna