This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
No, you cannot change a select list so that the value cannot be changed. What you could do is bind to the change event, and when it is changed, change it back to whatever you want. You could possibly get extra fancy and position a transparent div over the top of it (would have to use an iframe hack for IE) but that seems like a lot of work for little gain.
Final advice is if you have a select list that shouldn't be changed, don't show a select list.