You may want to have a look at microperl which was introduced as a new feature with Perl 5.7.0. This build incorporates the bootstrap feature of Perl which behaves similar to any other build of Perl, but does not incorporate Dynaloader XS module allowing the execution of C-based Perl modules or system specific functions providing you with a scaled down subset of perl which is perfect for hacking or porting.

If you are interested, there was an article on microperl written by Simon Cozens in Issue 19 of The Perl Journal here - This article has also been incorporated in the O'Reilly published "Computer Science and Perl Programming".