I am trying to get in to the legion fort to recover the chip but i am vilified by the legion and am finding it impossible to get in after catching the boat at cottonwood cove.
I tried wearing their uniform but failed miserably,so does anyone know how to become accepted by them as friends so i can just walk in,any ideas greatly appreciated

Try killing NCR for rep but of course then NCR will hate you or kill Powder Gang or wear legion armor and go in but it will be hard to get past their dogs guess just kill them all if you do not want to kill NCR or Powder Gang.

Um well you have a couple of choices.....

1) Attack the NCR and try to do some Legion side quests while wearing their faction armor. And also stay away from the dogs or anyone else who can see through the disguise.

2) Kill all the Legion and go there yourself. (It would be easier if you have a companion with you.)

3) Go to a previous save before you were vilified by the Legion. (not recommended unless there is nothing else you can do.

Although it's going to mess up some people, I actually think it's a good thing in an open-world faction-oriented game that you can make a decision to take sides too early in the game and mess up your chances of getting through it unscathed. I wouldn't want my hand held throughout the game, you make your decisions and if you decide to take on an entire army before you're ready you have to live with the consequences.

To the OP: if the Legion hate you, go do some side quests for the NCR to throw your lot in with them, gain a few levels, come back with companions and the NCR emergency radio, and batter your way through by force - that's the decision you already took when you got the Legion cross with you in the first place, and decisions have consequences, sometimes dire. Come back when you are stronger.