DLSW won't be a problem if you have a router permorming as one of the endpoints, however if your trying to get native SNA traffic through the PIX you'll be out of luck as PIX's are IP only.
I'm taking a guess, becuse the the question is here not in the security forum that you have the PIX securing inbound access from the WLAN.
My solution if this is the case would be to have a DLSW Peer router located on the outside of your Firewall to accept the LLC2 SNA traffic, and encapsulate it to the DLSW through the router.
Just a guess I hope it helps.
Tony Henry