by the way ... after replacing the IR-key battery, usually the car does't respond to it, and it has to be reprogrammed, but I have tried for my fathers E38 many times without any luck, recently my friend bought a 1999 540 and he also have the same challenge. do you have any step by step procedure?
I am not so familiar with E38, best E38 knwledge base is here
http://www.bimmerboard.com/forums/e38/