For those that have trouble with this and have not figured out a way to use the search function from their N810 I discovered a way tonight. (This is probably obvious to some so just pass on by if you already know)

Basis:
ITT site, Default browser, classic theme, Keyboard (N810 or external)

Procedure:
Touch and hold your stylus on 'search' (You'll see the circular progress thingy) until the context menu appears, without lifting the stylus, slide up to highlight 'open in new window' and then remove the stylus. The advanced search page appears. Scroll down to reveal the entry boxes, select the box you want with the stylus and then with the keyboard, enter what you need to search for. Touch the 'search now' button at the bottom of the page with the stylus.

There may, of course, be variations on this that also work so feel free to add your even slicker methods!