from memory, (it's been about three years since I used winroute).
you usually have in the adapters section 3 adapters, they are local internet and dialup.
the dialup is the VPN adapter. you can impoprt users from your AD to your firewall, (this is how you setup security on the built in proxy server).
I think that somewhere in the users section there is the option to allow dial in.
also, I believe that you might have to specify that user has dialin access in their AD properties.
then you have to setup the firewall rules too...
(if I still worked at my old job I'd just have a look at how I did it before and provide some screen shots, but never mind).