Hi Alex, you could try something like the commands below and see how you go. I played around with them a while ago and they "sort" of worked. I think from memory I had to escape double quotes in the html as \". And it doesn't automatically follow links to download images etc like the old MS OLE webbrowser did when you set the html using Object.Document.Write(ls_signature), but it might give you a place to start.
wb_1.EvaluateJavascriptSync('document.body.innerHTML="<H1>Some sample html</H1>";')
wb_1.EvaluateJavascriptSync('document.documentElement.outerHTML="<HTML><H1>Some sample html</H1></HTML>";')