the method is use for getting host is:
during lobby time when it displays "finding host", i flip my switch on until it stops displaying "finding host".
also what i have noticed when you are host: is that your body will freeze( on their screen not yours) and others will still be capable of moving.
the only difference of being host as apos to not being host is: as host you can freeze your body and it will NOT take damage when the switched is turned back off.( meaning when the switch is flipped on your body will freeze but when people shoot it, it will not take damage) however when you are not host you body will freeze and you will take damage when shot by enimies.
the only upside that i have found, again "i have found" with lag switching in mw2 is that you can use it to clear rooms, fields, and long hallways/ pathways.(ex. if you are host and want to breach the front door of estates main house. you would place your body around a corner, flip the switch, run inside the house and knife campers, then flip switch back on).
to practice your lag switching skills and becoming host. get into a 3rd person lobby (so that you can have a friend joain your session and NO ONE else!!) once in game meet your buddy somewhere, flip the switched and ask him what he sees.(flip your switch and run around and have him tell you what is taking place.)
i hope this helps...holly crap that was a ton of typing.... any reps or thanks yous would be awsome!!! ha