Routing

We have a VPN from CT to the UK utilising a VSU unit on either end. Communications are fine using the Cisco 1605 router and going via our Service Providers fibre backbone to the UK. Our KL office has now got a similar VPN to the UK office and comsare fine between those two sites as well. The problem is, how do we communicate with the KL network? It is not as easy as setting up a static route as this is not a PPP connection. Any feedback is very welcome. Thanks.