This is the feature which is missing in CRM. Althogh CRM has this inbuilt feature and they use this in Advanced find.
Now they are planning to introduce this option in crm 365 .
I am working on a HTML 5 control which imitates CRM multi-select control.
What it does?
It takes a option set field and renders it in the control.User can select the values from the available values.Selected values are shown in custom field.Just save the CRM form. Thats All :)
Demo is shown below.
