Ges123,
NW is terminal 2, UA is termianl 6,7,8. I don't know which terminal UA departs its flight to OGG, but I can tell you UA's terminal is infamous for the crowd, only second to SW.
When you get off NW, you need to catch Shuttle Bus A to UA terminal, I will estimate 20 minutes for this. Security check on UA, to estimate the worse, 50 minutes. I think two hours are enough for you to get the connection as long as you don't check in any lugguages at LAX.
I am not sure you can walk from NW terminal to UA terminal at this point. I know the security is pretty high on those parking structures. If you could, it will not be difficult because the traffic at LAX is really light now (they ban all private vehicles into LAX).
I went to OGG in May. Absoultely beautiful. Make sure you try the bicycle ride from the vocano. Also reserve the Old Lahaina Luau as early as you can. There are many discussion at the Trip Report about Maui. Do a search and you won't regret it.