Hi Nachiket,
I don't know Wicket, but I've heard that it is similar in some ways to Tapestry (which I've used quite a lot). I would guess that you would need some kind of Dojo plugin in Wicket to be able to use it, and also create wrappers for the widgets you would like to use.
As long as you would have access to some kind of 'pure' html page or part of page that you can modify, you can insert Dojo CSS and script resources in the same way you would in a stand-alone page.
Speaking of JavaScript knowledge, I have a chapter 2 in my book which gives a lot of basic JavaScript information and good to know things, as well as common problems when using JS and Dojo.
I think that JS is one of the most forgiving languages to learn, as you don't really need to understand everything you do or use. One good way to learn is to just copy in an example in a page and mess with it. Learn one small thing at a time, in your own pace.
Cheers,
PS
http://unclescript.blogspot.com/