Assigning only 1 IP from a subnet to a port

[#1]

Is it possible to assign only 1 IP from WAN1 or WAN2 interface to a Port interface? We have a 110C and I' m trying to do IPSEC VPN with a customer. We have a group of people who should use the VPN to access internal computers in customer' s network, and also we are accessing some computers in their network using the internet directly (not VPN). The tunnel works but they reported they have problems with Asymmetric Routing since we are using the same IP for accessing to their firewall for both through VPN and internet connection, and we should use a dedicated IP for the VPN. We have two circuits, WAN1 is Metroethernet being used for Internet traffic, WAN2 is G.shdsl being used for email traffic. So is it possible if I can seperate an IP from our Metroethernet block (212.174.x.x / 255.255.255.0) and assign it to Port5 for example?