JavaScript form referencing issue (again)

[will]

Hi chaps, one of those perennial questions.

I want to make a submit button (input type=image) roll over.
Referencing it is a pain.

The context: a complex navigation bar with a series of nav buttons and
a CGI search field plus submit button. Table construction in the bar
means that the neatest way to build the thing is to put a form wrapper
around the entire table.

Rolling over an image is trivial: document.images[imageName].src =
etc...

However, the submit image isn't having any. I've tried various
referencing tricks (document.formName.elements[imageName] etc) to no
avail. Questions:

*Can* I manipulate the SRC attribute of an image submit button?

If so, how do I reference it reliably for all browsers?

Best, Will

PS Have already considered and rejected onClick=Submit(): I need it to
be an input button not an anchored image. Sorry