[Peaty]

The only way to do it properly is to put it in the throttle body. Any other place you aren't going to evenly distribute it to each cylinder. Booster or PCV valve will only go to one or two cylinders. Seafoam has a new aerosol with a funky dip tube that makes it a lot easier now. I just did my kids 2001 OB not too long ago. Have a look here:

SEA FOAM SPRAY - 12 OZ. AEROSOL

and

If you go here and click open all:

http://www.seafoamsales.com/how-to-u...pray.html#nogo

I also have info here on ScoobyMods, you need to register to see the pics but it's free

http://www.scoobymods.com/showthread.php/idle-speed-control-valve-cleaning-3909.html?t=3909

Basically you remove the airbox off of the throttle body which is not too hard, a few hose clamps and two 10mm bolts and maybe a lower hose, fit the funky dip tub in as shown in the pics and assembly the airbox again with the dip tube in place (you'll have to cut the tube to length, pretty short after the black plastic part) then you can start the car and spray. When you let it sit take the airbox off again and remove the tube part. Sounds complicated but it's not.

 

[Peaty]

Or you can dump a can in the tank

That's not a bad idea but it won't clean the same areas. That serves a different purpose. Putting it in the throttle body cleans the upper intake area where normally only air and EGR gasses flow. Putting it in the fuel will only do the tank and in the motor from the injectors on.