The 4BD1TC is the intercooled turbo diesel used in non-US Troopers, but interestingly is also used in the Isuzu NPR heavy truck here in the US. So there is a great source of entire engines, cores and parts. You'd need to fabricate a functional hood-scoop for the intercooler, but I think that would just add to the VX's appeal.
Here's a good link (with many other good links) for biodiesel and other alternative fuel info: Journey to Forever - Biodiesel.
Just found this link today, a professional conversion company with an impressive track record: Elsbett.