Sure you can, but there are comparitively much fewer flights you could connect to out of LAS. If it's real, it's an odd choice of destination --
Well, at least according to Wikipedia (so not sure of accuracy of statement), "As of September 2008, Southwest Airlines operated more flights out of McCarran than at any other airport", serving 56 cities non-stop and with 233 daily departures (as of 16 July 2009).
Wouldn't this fit extremely well with Jetstar's target market?