You weren't very specific about how you're connecting everything so I'll point you to this.
http://www.dd-wrt.com/wiki/index.php/Linking_Subnets_with_Static_Routes _________________ Read the forum announcements thoroughly! Be cautious if you're inexperienced.
Available for paid consulting. (Don't PM about complicated setups otherwise)
Looking for bricks and spare routers to expand my collection. (not interested in G spec models)