You can pass click events with Watir pretty easily.  As far as
javascript is concerned, you _can_ directly manipulate it via watir,
but usually, why bother?

Now, for more advanced questions, and future ones, yea ask on the
watir mailing list.

Anyway, in this case, your problems aren't with watir, they're with a
_VERY_ poorly constructed website.  I just took a look at it, and I
mean, yuck.
Load it irb, and look at the page that way, everything is actually in a frame!
$ie=Watir::IE.start("http://www.runescape.com")
$ie.link(:text,/play runescape/i).click
#oops, that _should_ work, but it doesn't!  Humm
$ie.show_frames
  there are 1 frames
  frame  index: 1 name:
#Ahh!
$ie.frame('').link(:text,/play runescape/i).click
#yes. It's that bad/poorly written.  While there is a decent defense
of using frames, not giving labels and ids to things is just bad.
#ayway, that's the first of two play runescape links, you can get to
the second one this way
#and then use any of the regular methods on it you wish, like click or
flash or html or whatever.
$ie.frame('').link(:text=>/play runescape/i,:index=>2)

--Kyle