I dont know about a conversion but at a guess the easiest way would be a td4 conversion. But make sure if you change front gearbox/diff that the ratio matches the rear diff. I would guess you need to change fuel tank as well as some of wiring. I would guess it would be easier to get a written off td4 then you have all the parts available and can see how things fit together.
Good Luck and post how you get on.