That sounds like the upgrade version for the 396, which isn't the same. If that's also the version for the 246, then let's see whether other 246 owners jump in and say whether it's worthwhile to apply.
As for rebanding, all the manufacturers have yet to release details about how they're going to handle rebanding. As I understand it, there are a few rebanded Moto systems coming online (or are online) now, so we must wait to see when - and how - this is going to be supported 73 Mike
If the full name of what you're looking at is BC_VUP_v126.96.36.199.zip, that's only the firmware update loader. It's not a firmware update file. The current 396 firmware (V2.00.07) would not work in the 246. You'd get a version mismatch if you tried to load one for a different model like the 396 or 996 (the only two with recent updates).
The last firmware update for the 246 was dated 10/13/2006, and labeled BC-246T_V2_10.scn. Nothing since. Uniden has not released a rebanding update for the 246, nor any of the other DMA scanners (330, 396, 996, etc) as yet. While there are (as Mike noted) finally a few rebanded Motorola systems beginning to come online, the majority have not made their move as yet. I would guess Uniden is still in the testing & validation phase, before they schedule a tentative release date.