Playing technique is as important as the voice, and I think best achieved by using a pedal to directly control the glissando. You set the pedal to pitch control where full up is full,pitch, then typically depress it just a fraction ahead of hitting the note and and back off to full up to get control of depth and rate of glissando. You can also depress and reverse slightly right as you press the note to get that very Hawaiian down/up glissando. Mini pedal movement near full pitch can control the vibrato.
The range of the pedal needs to be set to suit the individual and will require some experiment but start with about a tone range. That way you only have to depress the pedal a little for normal depth, and not the whole way. If you set the range too big or small you will have trouble getting a consistent depth and speed on the glissando. Takes practice but it’s not too difficult, especially for piano players who are used to pedaling.
I’m afraid basic ability matters with stuff like this. Good players will probably get the hang of it in minutes, but novice and intermediate players might find that adding yet another thing to think about in real time might just be one thing too many.
Like every instrument on the arranger, even when mastered it will never match the real thing, but it will be reasonably effective.
Mike