jQuery in elgg 1.7


Does anybody know how to integrate jquery into elgg? I wanted to replace all checkboxes with something like http://jqueryui.com/demos/button/#checkbox and the dropdowns like this one http://www.hv-designs.co.uk/tutorials/sliding_menu/sliding_menu.html . An other pagination would be also very cool :-)

Oh, I'm using elgg 1.7.7.

Do I only have to add some code into the header? Or is there more needed?