perl-Params-Validate is branched but not available in EPEL4. The version from EPEL5 rebuilds fine on EL4. Could you please built it ?
perl-Params-Validate-0_89-1_el4 built
I've taken ownership of the orphaned EL-4 branch and bumped it to the latest upstream version (0.95). It should appear in -testing at the next push; feedback would be appreciated. https://admin.fedoraproject.org/updates/perl-Params-Validate-0.95-1.el4