If you want to compile E-UAE with IPF support, you need the 'Developer Distribution' from
http://www.softpres.org/download (the one including capsimage.h). Then configure --with-caps --with-caps-prefix=/path/to/where/you/extracted/the/archive .
I'm seriously wondering why you guys want to compile it yourself at all. IPF support, not being open source, is restricted to i686 and PPC systems. So if you're using another architecture, you're out of luck anyway. On the other hand, if you are using one of these two, you can just use a pre-compiled binary from
http://rcdrummond.net/uae/ .
In any case, you need to have libcapsimage.so.2 in a runtime-accessable place. Usually, it's a good idea to put it in /usr/local/lib . Instructions how to make the system register the library can be found in the README file accompanying the Developer Distribution archive.