I did this install on my 07 m35x. It wasn't too difficult. You would need your standard sockets, deep sockets (maybe) and breaker bar, and maybe a few other tools. I think there is a how to for this in this forum, not sure if it would be the same for the 03/04 M45 platform. I'm sure one of the moderators would be able to assist with confirming.
Here's the link for the y50