it sounds like you are on the right trail by setting up a plot style with all black. Just don't forget to turn on "use plot styles" in your plot dialog. I overlooked that one myself and it really threw me off.
Try looking on Cadalog.com and searching for files related to "xref". I recall seeing a routine on there that does what you seem to need. I hope all goes well for you, as I have also had to go through this with saved paths coming into play after moving a local drawing to the server...
