That's a pretty broad question mate
, but I'll have a go. If it's N/A to start with then I don't think it'll be easier than petrol. I'm going to start you off with some basics and any terms you don't know Google should tell all
.
You'd need to choose which type of turbo you're going for and what sort of power. You've got VNT or wastegate. The size of your engine and target power will best determine size of turbo. If you go to Garrett's website it'll show you the formulas to help you work this out.
You'd need to sort out oil feeds and cooling to the turbo. Perhaps uprate the radiator and oil cooler. I suspect the fuel pump will need uprating. With the extra power you'd need to think about an uprated clutch if possible. You'd need a turbo exhaust manifold. If your engine block shares similarities to the Punto turbos then you might be onto a winner there.
Management wise your stock ECU isnt going to be able to hack it. You'd either need to go Piggyback ECU like a Dastek Unichip Q, or standalone like Motec. The latter is going to be very pricey costing £1k+ just for the ECU.
As for places to buy things or get the work done try Demon Tweeks or Merlin Motorsport as two of many examples. The Derv Doctor is pretty handy so I've been told at doing pretty much anything with any diesel, but don't expect it to come cheap. In fact any turbo conversion isnt going to be cheap.
Anyway I hope that points you in the right direction
, and good luck with the project