Is this the part of the iso adaptor that fits onto the radio? If so the best way is to look at the markings on the actual radio or getting the model number and doing a search on the net for a manual. Hope this helps.
I got from ebay an ISO connector especially for the BX (description saying 2CV, Visa, BX, at least). This ISO connector had on the other end connectors to match exactly the original BX connectors.
No wiring necessary, simply plugging things together.