Tom, I'm using the following configuration:
access-list 101 permit ip x.x.x.x 255.255.255.0 y.y.y.y 255.255.255.0
(where x.x.x.x is the inside of my network and y.y.y.y is the ip address I'm asigning to the VPN users.)
nat(inside) 0 access-list 101
When I try to limit in the access-list the port, It is not possible, that is why i though I could do that with the IAS, if you have any other tip to do this please let me know.
Thank you