You need to create a new player file, like the Player_JumpJet but inside it, within the player dataBlock you need to set the following values:
jetEmitter = yourJetEmitter;
jetGroundEmitter = yourJetDustEmitter;
jetGroundDistance = distanceFromGroundtomakeDust;
If you don't add one of those into the new player dataBlock, then it takes the default value.