Burke hires them... so if you killed them, then obviously it's not possible to ask him to tell them to stop.
http://fallout.wikia.com/wiki/Talon_Company "A bounty may be taken out on your life, and Talon Company is one of the groups looking for you. However, even if they are not doing so, they will be hostile towards the player if encountered."
Better answer: Talon Company hunts you if you have good karma/killed Burke/alerted Simms to Burke's plans/defused Megaton's bomb, but they're always gonna try to kill you, and you can't ask anyone to have them stop hunting you. Don't worry about it though, they're rare and they're pushovers.
Long story short… If you have good karma Talon mercs will occasionally ambush you. If you have bad karma regulators will ambush you. The only way to stop both is to keep neutral karma. (Although Talon mercs are still present in the game even if you have neutral or bad karma, such as at Fort Bannister.)ReapTheChaos 22:23, January 29, 2010 (UTC)