Convert a XML string to a node

I have this situation where i'm creating a DOM doc in Javascript and
adding some nodes to it, that i want to pass to a param in a XSLT.

It works ok in IE, but it seems not in FF
(https://bugzilla.mozilla.org/show_bug.cgi?id=248025)

So can i pass this as a string instead and converting it to a node so
i can include it in my result tree?

Since i'm working on the browser i can't use extensions, so it seems
i'm on a dead end in  here.

Does someone have any thoughts?

Thanks.