Yes. You can use the "Death" or the "See Death" event. But first, you need to attach the event to the spawned Pawn/Player by using the "Attach to event" action.
The "See Death" event has two outgoing variables - Victim and Killer (don't know the correct naming atm). So you need to check if the Victim and/or the Killer is a bot/player.
But this type of modification of the gameplay should be done via a mutator in general.
class ReverseHandicapMutator extends UTMutator;
function InitMutator(string Options, out string ErrorMessage)
class ReverseHandicapRules extends GameRules;
function ScoreKill(Controller Killer, Controller Killed)
if (!Killed.bIsPlayer || AIController(Killed) != none)
Killer.PlayerReplicationInfo.Score += 2;