Most of the newer HP drives support boot from tape. I think they call it "DRTape". I found a little Questions and Answers section on their website - maybe it will help:
Tape Drives include: 12/24 DAT, 20/40 DAT, AIT 35, AIT 35 LVD, AIT 50, DLT 40/80, and SDLT 110/220. Tape Autoloaders include: 12/24 GB DAT AutoLoader and 20/40 GB DAT AutoLoader. DRTape is not supported on the HP DLT 20/40 GB tape drive.