I have not been able to test the booktype capacity, since "dvd+rw-booktype" keeps reminding me that :This program targets units of RICOH, BENQ, BTC and LITE-ON designs. /dev/dvd doesn't appear to be one. Exiting.
As you can surely imagine booktyping functions are vendor-specific extensions, meaning that there is no "generic" booktyping support. If you want to help, talk to Nu and ask if they can release their vendor-specific command set specification. A.