Reset oil service interval

Hello folks, I've recently become a first-time BMW owner, so please bear with me.
I'm sure this question is always asked, so I searched the board and found some information, but I'm still not sure I found what I need, again please be patient with me here.

I have an '02 325Xi. Out of warranty (50,000miles), so the dealer doesn't change oil and filter for free anymore, I do it myself.
I realize the oil service indicator counts down based on the computer's analysis of driving habits, etc, so I'm not looking to reset the interval to any pre-determined value that differs from whatever they have programmed.

All I want to do is reset the thing to start a new countdown when I change the oil and filter. Can someone explain a way that I can do this myself?

Thanks in advance.
Dave

here ya go . . .

http://www.bimmerzone.com/resettool.htm

Hope it helps ! !

You can also find them at Bavarian Autosport. Their address is www.bavauto.com. You can pick up Mann oil filters from them, too, since none of the auto stores around me stock any filters for BMWs.