Sorry, I don't know how. Your question proves that beauty is in the eye of the beholder! In a different thread, I was just lamenting that I find the JABB bari's too brittle ... IOW, I've always felt the attack is too abrupt. Go figure.
I'll be looking in to learn what can be done to massage the attack ... there's some real brainiacs on this site ... someone will hopefully help you.
The Garritan instruments, JABB Saxes included, have their attack controlled by velocity. Unlike standard MIDI, the volume isn't effected by velocity - that's all controlled by Mod Wheel (CC#1) - But if you want a sharper attack, pound those notes right on up to a full value of 127.