Hello,
I want to do Gannon's companion quest. According to wiki, I have to get into a certain point in the main quest in order to trigger it. Is it a must? Are there any other ways to trigger the quest?
I don't want to touch the main quests yet. I want to explore the entire world first before I try so. I also want to do a "hard save" then in each save choose a different main quest to follow it's path, so I would like in the hard save to have Gannon's quest completed already.

Any options or am I delusional?

You have to reach that point in the main quest, in addition to getting three dialogues from locations.

http://www.gamesas.com/index.php?/topic/1139709-companion-mission-sidequests/page__p__16662891__fromsearch__1&#entry16662891 I made about it hopefully it will give some useful information. Basically to give a "Layman's" definition you have to progress in the game to the point where you receive the prompt saying "This will commit you to the faction AT Hoover Dam." At that point you decline the offer and talk to Arcade Gannon about things.

Found it best to do the primary story then recruit Gannon at the end of everything then take him to the crashed Vertibird site then the Repcon HQ. At that point i'll talk to you about the Remnants and gathering them together.

To begin Gannon's quest, you have to be nearly completed with the main story. Almost to the point of committing yourself to the final battle. At that point you'll wanna take Gannon around to certain places on the map, namely anyplace or person that has anything to do with the Enclave. Visiting these places through exploration or dialogue will trigger Gannon to approach you if he is with you.

I'm not going to spoil it for you by telling you the people and places, but if you really must know, wiki can list them for you.

I must have glitched. Arcade's quest started shortly after bumping off Mr. House and installing "Yes Man" into the network. I was also at the stage in "For the republic, 2" where Col. Moore wanted House dead.

Darn, I wanted to do his quest. Cheers everyone, already visited some areas where he poped up conversations. I guess I will have to wait a bit before getting his quest. Thanks.

That's about right since you've nearly commited yourself to a particular ending. Installing Yes man and receiving orders from the NCR to kill house means you've already dealt with factions like the Boomers, Great Kahns, and the BoS.

They ask you to kill House before you deal with BoS. I know because I killed House for them, but then abandoned them when they wanted the Brotherhood dead.

Though that doesn't negate your point. You are pretty far along at that point.

I visited all places to trigger his conversations. Then I could do whatever I wanted, he remained calm. After killing Mr. House he started talking again and started the quest.
Oh... and I've done some parts of "for the republic II" at that point.