Auto-suggest, multi select box

Hi Andrea!
The plugin is great, works as expected out-of-the-box!

I have a multi select box field with very many values (hundreds), for which I’d like to make a text search field. Where do I need to replace the current box with a text field?

Also, I’d like to add an auto-suggest, due to the high number of options. Like, after the 2nd letter, show all options beginning with this letters in a drop-down menu. This corresponds to the behavior of a drop down select box – just that I need multiple inputs. Do you have a hint, how to achieve this? Do you offer custom development for that?

Best