I too was unable to install the ipk of perl 5.8. But, if you install zaurus-debian a full install of 5.8.4 comes along with it. That only works while you are chroot'd into debian of course.

I've got 5.6 installed for little bits & pieces when running in PDA mode, for anything more serious I can start up an X server and run in debian.

(C1000 with 1GB SD card & sharp rom)