This is a bit of an out of date / late response - I have been playing around with synthetic DNS records and use a redirect for my users
I have a registered host: servername.com
I then have subdomain forwarding set to say:
www.clientserver.com -> servername.com:8080/AwareIM/logonOp.aw?domain=ClientApp&logonPage=logonClient.html
I've then used created a copy of the logon.html page (the one with just the username and password) renamed it logonClient.html to make it be more client specific.
When the client uses the www.clientserver.com url it then loads the login page.
What I haven't managed to look into yet is masking the URL to stop it from changing from www.client.com to server name.com:8080/AwareIM/etc etc.
This is probably teaching everyone else's granny to suck eggs but I just figured it all out...