Set field name with VBA?

[mandanarchi]

I know Visual Basic and VBA aren't quite the same thing, but I'm having no luck anywhere else.

[code=vba]
Set myHTTP = CreateObject("m sxml2.xmlhttp")
Set myDom = CreateObject("M SXML2.DOMDocume nt")
myDom.async = False
myDom.Load (myxml)
myHTTP.Open "POST", "<--website removed-->", False
myHTTP.send (myDom.xml)
[/code]

I've been using this code for a while, and it works fine.
'myxml' is an xml document created on the fly, which is fine; that works.

One of our suppliers requires data to be POSTed to them, with the field name set to 'xmlmsg' and sent as 'multipart/form-data'.
I'm sure there's got to be a way I can set this using VBA.

I know of the [myHTTP.SetReque stHeader "name", "value"] code, but it doesn't seem to work. I think I might just be putting the wrong details.
I think I tried

"Content-Type", "multipart/form-data; boundary = " & boundary
"Content-Disposition", "name; 'xmlmsg'"

But I just got errors.

I've hunted and found plenty on headers, but nothing relating to VBA.
Does anyone know, or know of a place I can find the info I'm looking for?

Thanks
Mandi