auto complete with checkbox

Hi,

I am trying to use the text_field_with_auto_complete but i need to
extend it.
So i want to have a scroll bar, so if the list becomes too long i have
a vertical scroll bar.
I tried giving my DIV some height but it is giving me horizontal
scroll bar and not a vertical one.

Also i want auto complete but at the same time also have the ability
to select multiple values from the auto complete list. So i think
essentially this needs to be done by having a check box in the auto
complete list.

Has anyone tried any of this.

Any help would be useful to me.

Neha