Yes, but the backup will have to be carried out on the AIX box in order for it to have access to the tape drive.
Check out Mondo
, which can backup to CD, DVD, and tape.
The sort of process you would need to do would be:
Mount the directory from your HPUX box (via NFS or equivalent) on your AIX box
Use Mondo to back that directory up to tape
Unmount it again