Pretty easy to do. 2 cans of Sea Foam $6.98ea and about 8 gallons of gas $3.49 gal. All you need is a piece of hose and a really foggy day with no cops on the road.
I poured 1 can in the gas tank, and half of the other can in the oil. Then disconnected the brake booster hose @ the intake manifold, connected an 18" length of clear hose to the fitting that the brake booster hose was connected to, started the car and had a friend keep the RPMs around 1500 while I let the motor suck down the other half of the second can. I was pretty suprised at how much suction the intake manifold produced. I never actually had to submerge the hose into the cocktail as the engine litterally inhaled it from about an inch away. The car started smoking pretty bad about halfway through the drink. Once it was finished consuming the 8oz of Sea Foam, I shut her down and waited about 45 minutes.
I timed things perfectly as 8:00pm rolled around, the fog rolled in from the beach and the sun went down. Took her for a 10 mile stretch down the 101fwy and back, no more smoke and she revs smooth and evenly.
The motor only has 28k miles on it since it was replaced under warranty by BMW when the original owner had it. Tomorrow I'll put about 100 or so miles on it delivering pizzas, Thursday the o2 sensors that I ordered from KO Performance should arrive at which time I'll install them, change the oil and take her in for a smog check. Not very exciting and no real noticable results. Probably didn't need it, but I feel better knowing that my engine is clean on the inside. Especially since I stretched this oil service interval about a thousand miles further than I usually do.
Just Sea Foam'd my engine 
Threaded Mode