Get the biggest LAN you can somewhere in NA, persuade the top teams to attend, persuade a large portion of the community to attend.
In particular getting communities to attend is important, at i-series the big ones from EU like TC, Nervous Energy, Clanda, Kritzkast, UKCS all attend, these being mostly UK based communities but an impressive amount of non-UK people still come.
But also what is recognisable is the amount of players from the Prem/Div 1 level that come, from ETF2L S15:
Team Epsilon, Broder/TCM/Infused attended with their full lineups, SOLAR attended with all except Medic, had their old Medic there. Majority of RLM's S15 lineup attended with different teams, 2 guys from LMS came (the non-Russians). Then in Division One, Half of Reverto came, half of my team, Furbo Pandas came, Did I stutter had most their team come, Least one guy came from every team, in the end you've got like 40-50 current top players from Europe in attendance, mixed in with some ex-greats of past times gone by, it's more than enough talent to create several good teams and a lot of these people travel from around Europe as well.
To relate this to North America, if you held a LAN somewhere fairly central with good transport links, I can't really comment but around the East Coast and got most of the community from that area to attend, then try to get least half of all your top players there and still get your top teams like HRG, Mix^, AG...etc then you'll have a heck of a big community LAN with great players in attendance. I think the sheer size of the US would affect it a lot, UK one of the most Western parts of Europe so we don't get too many Eastern EU people come, if the NA community were to do the same then parts of the US would be neglected, but it's really about getting as many people there as possible.