You might be able to do that using the remapping ability that is included with MicroStation V8 -- see ColorTblWt.dgn that's
delivered with the product.
BTW, we host and monitor a number of discussion groups specifically related to Bentley products and services. If you haven't yet,
you might want to check out http://www.yqcomputer.com/
Phil Chouinard [www.Bentley.com]