I have not actually done it yet, however I have a 300tdi engine and a series without, all my research shows that yes you can.
200tdi fits the series a piece of wee without the turbo, no welding, no mount chopping or bulkhead mods, you can fit it straight in, if you want the turbo you can use a deffender turbo manifold (I think).
300tdi fits the series bellhousing ok, but the mounts do not fit, you can however grind the mounts of the donor disco and use them, the turbo does fit better on a 300, but you have to mess with the front to get the intercooler rad oilcooler in from the donor disco.
If your new to the game I'd advise a 200tdi without the turbo, its a weekends job for a enthusiast.
There are all sorts of other threads about this, do a search.