Just done it to my 1.9 sporting, dead easy, locate the plug inside the panelling where the unit is going to go, push the unit in the hole and plug it in! took 2 minutes. The part number is 0735358849, cost £7.85 all in.

If you have a rear fuse box then it is an easy fit, but it depends what model and or options you have to whether you have the fuse box in the first place

if your have rear electric windows, electric sun roof, factory fit sub woofer or power electric front seats then you will have the rear fuse box