so you want to establish a Network connect tunnel and than use WSAM to connect to an internal resource? What will that give you though? if you disable split tunnel (like you should be doing any way) all your traffic is being sent to your work and WSAM is going to go the same way on the same tunnel.
We have the same issue in our network. We actually have alot of users running WSAM through a NC tunnel today, and this works fine, -the only problem is that Juniper apparently does not support this. Actually it seems like noone gets the need to use both of them at the same time, not even Juniper.
Anyway, -we have a dialogue ongoing with Juniper about this at the moment
I see that this post is a little old but if this is still an open issue for you I can keep you posted when we get some answer from them.