xsiframe linker and NTLM Negotiation

[JT]

I have done some searching and couldn't find anything similar. So here goes.

My application is using GWT 2.4.0 and GXT 2.2.5 and the environment in which the application will be used has Active Directory (LDAP) present. So in order to access an application the user/browser needs to go through the NTLM negotiation process.

We are attempting to use the 'xsiframe' linker so we can do cross site scripting (ie. have the HTML page hosted on one server and the JS/server code on another server).
The application load up correctly when it is deployed, however any attempt to call a GWT RPC service fails. After tracing, it looks like the RPC is making the remote service call, but due to the NTLM negotiation the server is returning a 401.2 status code and the RPC never attempts to do any further negotiation.

I have attempted to use the GWT RPC Plus project, and have managed to get it to work for FireFox, but it fails for IE (the content is returned to IE, but IE isn't picking it up). This project uses an iframe for communication and injects a form, setting the enctype to 'application/x-www-form-urlencoded'. Upon the form being submitted it encounters the 401.2 from the server, but then continues to successfully go through the NTLM negotiate process. Finally returning the results to the client.

My question is, what would I need to do (and how would I go about doing it) in order to use the same method above for my RPC communication with the xsiframe linker (ie. attach a form and set the same enctype)?

Thanks for any and all help.

JT.