Definitely - you really need to preheat the diesel using a heated filter - you can find these on ebay - or you can run on a 50/50 mix - just watch out in very cold weather for gelling.
TDs will also run on heating oil but you need to put some lubricant in the tank to keep the injector pump happy (you really ought to do this anyway in UK with all the low sulphur fuel being sold) - once biodiesel becomes available on forecourts this problem should disappear.
Let us know how you (or your friend...) get on.

All German made diesels have been designed to run on biodiesel for some years now - that doesn't say that they will run well on pure veggie oil - but the BMW lump just happens to be good at it - the injector pump is "veggie safe" - so long as you pre-heat. There was a guy on the Yahoo Omega forum who ran his for some years almost exclusively on veggie oil and claimed it ran smoother than with forecourt fuel (plus the satisfaction of keeping Mr Browns hand out of his wallet!). As I mentioned in my first post - current low sulphur diesel as sold on Uk forecourts is BAD for your injector pumps!
Personnally I run mine on forecourt fuel - but that's because I'm paying less than 60p a litre for it in France (and it contains min 5% biodiesel, so no problems with lubrication). If I was in UK, I'd be running on heating oil( 30p/litre) plus lubricant because veggie oil is a pain to get in large quantities (and does have drawbacks in cold weather) and biodiesel has to be manufactured in the garden shed!