*Disclaimer* - I am not liable for anything you do to your car. This is just a basic walkthrough.
Tools Needed:
- Needle Nose Pliers
- Half a can of Sea Foam
- Solo cup or funnel with a REALLY skinny neck
- Any assistant capable of keeping their foot on the gas and maintaining 2-3k RPM.
Process:
1) Open the hood and remove the cover over the brake fluid reservoir.

2) Locate the vacuum line needed to do this task. Move the hose clamp circled in the image up a bit to allow the hose to be removed. My hose was stuck on pretty good so I had to spray a small bit of WD-40 at the edge of it and wiggle the hose to get it budge and then it slid on and off nice and easy.

3) Now fill your cup (or get your funnel ready) with half a can or so of Sea Foam. I personally did a full cup, and it was like 70% of the bottle, maybe slightly more. Have your assistant start the car. With the car running, have them get the RPM's up to like 3k. Once you remove the brake booster line (with the car running) the RPM's will drop a smidge. When you submerge the hose into the cup (to suck up the Sea Foam) or pour the Sea Foam in via the funnel, the car will try to stall. Make sure they prevent it from stalling by maintaining the RPM's as needed.

4) Immediately after the Sea Foam is sucked up/poured in, shut the car off.
5) Now let the car sit for 30-60 minutes and after that time has passed, start it up. It may struggle to start, keep at it. Eventually it'll fire up. Give it a few minutes to start idling properly and now start revving it and enjoy the smoke show. Once the smoke subsides a bit, take it for a brisk spin down some highway roads and give it the beans

I forgot to take a video (but boy, did my M56x smoke)...so here is one of my 2007 M35x that I Sea Foamed back in the day. My M56x had 65kmi on it compared to the M in the video which had like 34kmi. I had like double the smoke. It was awesome.
http://www.youtube.com/watch?v=McLwRh_c3us