You can use Cache::Cache to save your data structure (this is what Mason uses for caching).

Your host seems to be running Apache 2. mod_perl 2 (which is required if you are using Apache 2) is still (mostly) in development and AFAIK most of the handler modules on CPAN are targeted at mod_perl 1.x, so the fact that you are limited to registry scripts is probably not something to worry about.