The easiest way is to load the KS combo instruments. That way you have all your articulations loaded in one slot. Then, when you enter an expression symbol you can edit it and set it to play that keyswitch note. The keyswitch notes are conveniently labelled so you should have no trouble identifying them.
If you choose to load separate articulations into separate slots, just make sure that all your articulations are loaded into the same player. Then in the tracks window, set up that instrument with each articulation on a separate voice and channel. Then when you edit your expression or articulation symbol, just select voice instead of keyswitch. Hope this helps.