Okay, some possibilities. I've no experience of Perl4 so if anything I suggest is dodgey or wrong hopefully one the guys or girls here who has that experience will correct me.

1. Have you checked the distribution CD's for Tivoli and looked to see if they included any of the more common modules?
2. If not, you can probably still get hold of the Perl4 versions of some of these modules on CPAN or somewhere. I did a simple google for perl 4 module and found this which would be a good starting point. The installation doesn't seem to need a complier, but I didn't look too hard.
3. If you really cannot use this module, then the source code will give you a good idea of the work involved in writing you own replacement.
4. If the system you wish to run the script on is not just one but many servers, and you cannot get permission (short-sighted though that would be) to "install modules", then probably the simplest solution would be to install and develop a Perl 5 solution using ActiveState Perl in your lab or on your workstation and then use the AS pl2exe utility to wrap the perl 5 .pl file and a perl 5 runtime into a single executable and distribute that.

   Problem solved I think. No dependancies. No possibility of interfering with your existing Perl 4 codebase. Worth a look?