Integrate with factory alarm?

Does anyone out there know if I can connect the horn output wire from my keyless entry ( - ) to a wire on the factory alarm siren?  I have a 96 Jetta GLS and I'd like to use the factory siren/horn for confirmation chirps.

Thanks,

SST 

connect the keyless (-) horn output to a relay, then connect to the Jetta's horn trigger wire (BLACK / YELLOW, behind fuse box) the Jetta horn trigger is positive so wire the relay like this:

85 = (-) horn output from keyless

86 + 87 = 12v (+) fused

87a = not used

30 = out to BLACK / YELLOW Jetta horn wire.

now IIRC, with the older VWs, the key had to be ON in order for the horn to work (pretty stupid idea if you ask me) so you "may" need to go direct to the actual horn wire and not just the trigger wire.