I've just realised why it is that I've had such a nightmare trying to get hold of the SVN version and build an installable version.
It seems the documentation here:
http://dev.virtuemart.net/cb/wiki/1363... and in the 1.1 dev guide (PDF) too
... is out of date quite significantly...
There are no longer any build scripts in the SVN version but instead a very important "HOWTO.txt" which is up to date but requires a fair amount of re-reading to understand.
Can I suggest that someone does a little wiki and doc editing to bring this lot up to date... I went down quite a few blind alleys until I tried a methodical "read everything, believe nothing" approach.