So here is my scenario.

After doing the quest for Cass and killing Alice McAferty or whatever, the NCR is not very happy with me. And now after doing the quest for Yes Man in Gomorrah, I went to the bosses and had them kill Chico or whatever his name was.

So now I am also shunned from Vegas and had to sneak through the monorail to even get in anymore. So apparently I am aligned with the Omerta's and their plan to take over/kill Vegas. What I am wondering is can I still go join the Legion as well with already being with the Omertas. I've already accepted that this character is going to have to be evil just curious if I can join both of these "evil" factions.