Yes, I believe you can pull it apart and on the back of the handle there is a C clip. once that C clip is removed you can slide the old button out and replace it with a key. My suggestion would be to buy a pair of door locks and replace both so the keys match. You can also buy a lock set so the ign matches as well.
http://www.fredstruckparts.com/Produ...r-Handles.aspx
In the drop down part # CDL-6425 is the 2 door lock set.