A4 central locking

[stonie]

I know similar questions have been asked before but not sure if i have come across my exact answer.

I have a 1996 (B5) A4 1.9TDi I already have central locking but am looking at installing an aftermarket remote central locking unit. can any one give me clues on wires and colours i need to look out for when installing this. i know where the central locking pump is located and this is a single vacum pump type. the system i am looking to install is the VT500TWL keyless entry system.

Any help would be appreciated+++