You should see this somewhere in the ioreg output:
| +-o BT <class IOACPIPlatformDevice, registered, matched, active, busy 0, retain count 6>
| +-o VALZ <class IOACPIPlatformDevice, registered, matched, active, busy 0, retain count 6>
(you may have VALD, but that shouldn't matter).
You can try loading the kext and then unloading it. It doesn't need to stay loaded to work. After loading it the first time, you should get the Bluetooth icon in the taskbar.
in /var/log/system.log, you'll see something like:
ToshibaAcpi: instance=0x3dc8900 provider=0x347ca80 'VALZ'
ToshibaAcpi: status reg = 42c1
I've built this on 10.4.8:
Darwin 8.8.1 Darwin Kernel Version 8.8.1: Fri Nov 3 20:57:08 GMT 2006; dima:xnu-792.13.8/BUILD/obj/RELEASE_I386 i386 i386