I've put a lot of effort into trying to stay neutral, but I seem to have angered Caesar's Legion...now they're throwing assassins at me! How can I get back to having them ignore me, with a neutral fame/infamy? (I am willing to use cheat codes as a last resort, but can't find the right one)

You could dress up as Legion, seek out legion outpost and perform quests for them I suppose. Also:

********Major Spoiler*********





After you meet Benny for the first time in the game, both major factions will offer you olive branches and re-neutralize your karma with them.

good to know, thanks...glad I found out now. I was JUST about to go meet that slime ball.

No. After i meet with benny, and he sent four assassins after me - no-one showed up <.<

wait...does this mean i'm screwed? no more neutrality??

or do things get re-neutralized? i'm confused...

No, everything is still reset. There are multiple ways of dealing with Benny when you first meet him, but no matter which way you do, you are still "reset" with the major factions.

All I did was walk around a little bit in Vegas after dealing with Benny and eventually representatives from the NCR and the Legion came and offered me a chance to be neutral again.

sweet! thanks for clearing this up...now i don't have to do worry about doing missions in Legion territory. A quarter of the map just opened up for me! XD

What do you mean by everthing is "reset"

Am I gonna lose my good rep with the NCR and FOA as well? I aint never heard of this.

No, I mean if you are Villified or something bad like that, then the major factions will say "Forgive and Forget" and you are reset to neutral. When I got done with Benny on my 2nd playthrough, I still had Idolized faction karma with the NCR, but my Villified faction karma with the CL was reset to neutral.