Anything is possible as they say, but it would be so much work and cost you would be better off either selling it and buying a diesel, or installing an LPG kit onto the current car.
You would have to change just about everything to convert to diesel (including gearbox, engine mounts probably, pretty much all the electrics including those behind the dash and the ECU, fuel tank, fuel lines, fuel filler, exhaust, instrument panel, and that is just the stuff off the top of my head!