You should just need the 5 vw wires, 1 terminates to a ground point, the connector it mentions is the little block that connects to the OBC switch.
This is the guide I used :
Pelican Technical Article: Boxster On Board Computer (OBC) Upgrade / Boxster Turn Signal Switch Replacement - 986 Boxster (1997-04) -
I used these :
vw/audi wires : 5 x Part 000979009E
BMW Connector : 1 x Part : 61136909058
Follow the guide, took me approx 2 hours but I was also changing to a 996 Cluster.
Regards
Dan