Juniper tends to have pretty good documentation in their knowledgebase, on how to configure equipment for different situations. I recently had to setup a VPN between a Juniper SSG-140 (at HQ) and a remote Cisco PIX. Going to Juniper's knowledgebase, you would most likely come across the article: http://kb.juniper.net/KB4147 . This article describes setting up a "route-based" VPN between the two devices. I believe these directions would work if you were trying to connect one subnet on each end.