Theres a couple of ways you could do this, I havnt used the CrmRestKit but I'll assume this lets you issue all the same calls as if you were not using it.
You could issue a FetchXml query, Markus Blog has an example of how to do this.
You can use the Stunnware Tools 4.0 to help with the FetchXml. Stunnware > Products > Stunnware Tools 4.0.
Or you could also use an OData call, Lakshman has an example of how to do this, he also includes a link to an OData designer.
The Msdn also has some more information on this: Data Access Using JavaScript.
Hope that helps