I'm pretty sure, all peugeot's have the same wiring schemata.
I've got a peugeot 406 and also found a pretty special wiring schemata.
It's an ISO connector but some pins aren't the same as they are on the empeg and usual ISO-connectors.
In the car's handbook I found a documentation about the pins of the connector. Did you already have a look in your peugeot's handbook?
You should have 2 or 3 connectors:
1 iso connector for connecting the head-unit to power, headlight etc
2 connector for the amp (speaker outs from the headunit)
3 connector for the cd-changer

maybe you could find a wiring schemata for your head-unit, then you'll know how to connect the pins.

hope that helps a bit...