Well, I hope you don't miss this message. This is an ooooold topic, now.
Anyway, I'd like to say my point here.
I don't believe there is so much interest in Objective C. The preprocesor you got is really outdated. There is no C++ preprocesor neither (I were recently looking for Cfront, the original C++ "compiler" made by Stroustroup and had no luck). I were interested in Sather too, but it's definitely dead.
The only active preprocessors out there for LCC-Win32 nowadays are SmartEiffel and that's all. Would be great to compatibilize to Pelles' compiler, but I tried and it's a pain in the ass.
But Digital Mars' D language has an open source front end. Would be great to program in D and generate PocketPC binaries from it. But a single D file should generate many C files to process. It would be great if the preprocessor of D language not only would generate C files, but also compile them.
So the conclusion is... why not to put pocc and polink functionality into a DLL, so compilations could be launched from processes, and make pocc and polink mere frontends for that functionalities. This way, you would have a funtion "Compile" on POCC.DLL that would take a buffer with C code, and would return a buffer of compiled object code. The reading and writing of files would be managed by POCC.EXE and POLINK.EXE.
I think this would make easy to create _good_ frontends for any language, having PellesC as its backend processor.