If you don't want to integrate your code into the AROS CVS (yet), all you need to do is set up a crosscompiler. In order to do that you can compile AROS itself, in which case the crosscompiler (a fake one, but which does the right job) is automatically set up for you under the
bin/linux-i386/tools/i386-linux/
directory, within the toplevel AROS source dir.
There you'll find i386-aros-gcc, i386-aros-ld and so on which you can use to make your own programs runnable under AROS.
Hope that helps.