becker indy satnav speed connection?

[El Donkey]

I have a non pro becker indy unit. i believe they need to connect to a speed sensor to work? car is a 97 w202 c280.

I will also need to buy an antenna and map disc. i assume any of the gps ants off ebay will work fine.

So where and how do i connect up the pulse, assuming the car has one?
Thanks