Issues with textbox focus

[gyhoo]

I have to use a piece of software at work that is browser based and is not well equipped with keyboard shortcuts. In fact it resists all conventional keyboard navigation techniques - tabbing, searching and clicking with Enter key etc. - probably because a lot of the links and buttons are generated dynamically depending on which part of the site you are on. SurfingKeys has been a life saver in this regard.

There is just one issue that I cannot find a way around. On each page, focus defaults to a textbox. Pressing Esc removes focus briefly (a fraction of a second), before the the site forces focus back into the text box. Is there a way to override this?