It should not need any reprogramming.  The programming teaches the car to
recognize the signal from specific remotes.  there is no programmable logic
in the remote itself.

Why do you think you need to reprogram it?  If it does not unlock the doors
after putting known good batteries in it,  the remote is probably bad.

All that being said, the directions for programming the car to recognize a
remote are contained in the Helm manual.  I have also had success by simply
walking into the dealer's parts counter and asking them to print out the
instructions for me (free).  I have the sequence for the '96 Odyssey.  It
might be the same.  I'll send it to you if you want to try it.