I have managed to hack a gallery template for the NextGen plugin in WordPress so that it renders as per gallery in CSSplay.
You can see it action here :
I am feeling rather smug with myself as my understanding of PHP is close to zero.
However, there are one or two things I would like to get like perhaps an image counter (x/y) and for a further development be able to make it render a tabbed gallery (go to http://www.cssplay.co.uk/menu/slide_show.htmlfor an example). If there is anyone who understand PHP and can improve on my script I would welcome the advice.
I have made the script and styling available for download go to my blog page for details.