Jake,
Judging by your model number, it won't accept 480p. Toshiba 4/3 sets that will accept 480p are all designated as HD-ready. Model numbers should be XXX71, XXH80, XXH71, something like that, not H60.
Check your owner's manual for any reference to High-Definition capability.
If it's not HD-ready or HD-capable, which should be prominently mentionned in the manual, it won't support 480p.
If there's no mention of HD capability, you don't have it and it won't accept progressive scan.