After I started reworking the whole thing from top to bottom, I also decided to switch from the IMHO totally awkward an much less intuitive XPath to the much more beautiful CSS3.
From now on, Dome will (almost) fully support CSS3 selectors and even some extra stuff that might come in handy but is not specified in the W3C standard.
As soon as the wiki is up, I'll post something on the differences between the standard and the Dome implementation.

Greetz!