Sure - just put the clock on your slide master. There are a number of ways to do this. The first, and probably easiest method, is to use a series of word art objects layered one on top of the other and animate them to appear at the appropriate time.
You could also use VBA, but then there are a few questions to sort out how you want it to work. You could also Google this and get some good results.
Tom
Born once die twice; born twice die once.