Kinda crazy answering my own post, but after a bit of digging around I found it.
Looking through the Makefile for sysvinit, there's this line: cd $(ROOT)/usr/bin; ln -sf last lastb; chown $(BIN_COMBO) lastb
Now, that soft link is missing in Pat's doinst.sh script. All the other soft links are there, just not this one.
Cheers,
Eddie