Unlocking with UI43Api.dll would allow you to use a camcorder in webcam mode without doing the swtch, so long as you remain in webcam mode. If you wanted to connect to the cam in Ops again, you'd have to switch drivers first (and then switch again afterwards)
Mr.MP3:
I took a look and I think it's not entirely as straightforward as translating one of our apps' unlock to UI43'ese, as there is no equivalent to the 0xfe and 0xff commands. Check out morcheeba's page for a summary of the USB commands and unlock process:
http://www.maushammer.com/systems/cvscamcorder/usb.html (it's worth noting that he lists 0xff as I43_GetLong, but the UI43Api.dll he linked to actually uses 0xfb for that command)
It may be possible to unlock by just by assuming a reset key and sending a reset-key response via a bunch of I43_SetWord/I43_SetLong commands (0xfa) without anything else. I'm not 100% sure that this would work with all firmwares, as I haven't looked at the disassembly of the unlock mechanism for months.
If 0xff and 0xfe are required, then there might be an out by using the I43_DebugOtr command, which seems to send whatever USB command index was passed to it as an argument.