how difficult is it to replace the timing chain cover gasket on a 02 bmw 325i

There should not be coolant leaking from your timing chain cover. I believe your water pump is adjacent to the timing chain cover. You should inspect it for a leaky gasket or a compromised hose or hose connection.

thanks. The hose connections look as if they were leaking but, just above the water pump there's a white flaky area & it's also rusty looking with streaks. I don't know if it's common to get a leak from the head gasket on these vehicles. I pressurized the cooling system & the pressure held. the vehicle would get hot in a few minutes. i just don't want to reassemble & be stuck w/the same problem.