Controlling HTMLviewer?

Is it possible to emulate the functionality of a greasemonkey script in Firefox using the HTMLViewer control? I need to be able to make a browser with an add-in that helps end users to fill out forms, select items and trigger events (submit buttons) on web pages for a web app that I do not control (the web app is made and hosted by a large corporation, but my clients would definitely benefit from something that would help them use that web app).

It would be great if I could use XOJO to write a single app for most platforms that would allow me to supply this.

You could but you would need MBS plugins unless you use the IExplorer OLE on windows, make another app for Mac with some kind of subclassed gecko control (which would work on linux as well).

I would recommend setting the HTMLViewer renderer to WebKit and then just use the ExecuteJavaScript method to do what you need to do (which is pretty much all greasemonkey does)…