How to set username and password before redirecting to a RESTful webservice

I am a .Net developer who has developed a webservice used by my ColdFusion colleagues. They are using ColdFusion 9 but I'm not sure if they have incorporated any of the newer features of ColdFusion in their apps. Here is a snippet of how they have been invoking the webmethods:

<cfscript>                      ws = CreateObject("webservice", "#qTrim.webServiceName#");                      ws.setUsername("#qTrim.trimAcct#");                      ws.setPassword("#qTrim.trimpwd#");                      wsString=ws.UploadFileCF("#qTrim.webserviceurl#","#objBinaryData#", "#qFiles.Filename#", "Document", "#MetaData#");             </cfscript>

As I understand things, the .setUsername and .setPassword correspond to the Windows credentials the CF Admin set when the URL of the .Net webservice was "registered" and given its "name" (for the CreateObject statement above). I have 4 webmethods that are all invoked in this manner and this SOAP protocol works adequately for us. Please note that this ColdFusion web app authenticates anonymous remote internet users by prompting for a username and password and compares them to an application database (i.e. Microsoft calls this "forms authentication"). Because only a few Windows domain accounts are authorized to call this .Net webservice, the above code always uses the same username/password constants and it all works.

My question involves the newest webmethod added to the .Net webservice. It requires that callers must invoke it as a RESTful service which means it must be invoked by its URL. Here is a snippet of C# code that invokes it from an ASP.NET webclient:


            string r = txtRecordNumber.Text;
            string baseurl = "http://localhost/sdkTrimFileServiceASMX/FileService.asmx/DownloadFileCF?";
            StringBuilder url = new StringBuilder(baseurl);
            url.Append("trimURL="); url.Append(txtFakeURLParm.Text);
            url.Append("&");
            url.Append("TrimRecordNumber="); url.Append(txtRecordNumber.Text);
            Response.Redirect(url.ToString());

I assume a ColdFusion script could easily build a full URL as above with appended querystring parameters and redirect. Is there some way for the CF code redirecting to a RESTful webservice (by way of its URL) to set the Username and Password to this Windows account mentioned above? When the DownloadFileCF webmethod is hit it must be with the credentials of this special Windows domain account. Can that be set by ColdFusion someway to mimic the result of the SOAP technique (the first snippet above).

I hope my question is clear and someone can help me make suggestions to my ColdFusion colleagues. Thanks.