Mac OS VPN server routing

I am a total newby with Macs. I have set up a Mac OS VPN server (both PPTP and IPSec). When connected to the VPN, I only need to access shares on the VPN server nothing else. I would like to be able to route all internet-bound traffic through the default gateway of my local network, not the VPN network gateway.
I need to set this up for both Macs and PCs.