Sharepoint 2010 On-line Pass-Through Authentication

Hi,

I'm using MS Cloud SharePoint solution and one of the disadvantages is that it requires all tenants to use the exact same login page (no custom branding allowed).  I found some links using pass through authentication solutions (i.e., Claims-Based Authentication):

http://msdn.microsoft.com/en-us/library/hh147177.aspx

http://code.msdn.microsoft.com/Remote-Authentication-in-b7b6f43c

http://blogs.msdn.com/b/cjohnson/archive/2011/05/03/authentication-with-sharepoint-online-and-the-client-side-object-model.aspx

I basically would have my own login page and pass credentials through to SP for authentication.

Has anyone tried doing this to any success? Before I put forth the effort, I just wanted to know whether this was a lost cause or not.

Thanks,
blue