Is there a way to set up a computer that is connected to multiple remote networks (via vpn or something else). I need the functionality of being able to remote in to one multiple networks at the same time.
If the remote locations have public IP ranges then you can just do this. No extra software needed. Establish as many remote sessiosn as you want.
If they are behind a NAT (and most likely using private IP ranges) then you will have to establish a tunnel to them. A VPN is the easiest way to do that.
If you need multiple tunnels or VPNs at the same time then just start multiple VPN connections and make sure that none of these changes the routing table, other than setting a route to the remote network. (E.g. no changing of the default gateway, no flushing of all other routes except the one that the VPN software just created).
There is one catch here. If you need to VPN to multiple sites and they are using overlapping IP ranges then you are out of luck. (which is a reason a sane site should not default to 192.168.1.x or 10.0.0.x but choose something semi-random from the private range in RFC 1918.)