CUSTOMIZE multiple selection

Hi,

I created a text field on screen for input selection,

e.g field auart for aufk-auart.

i.e parameters s_auart type aufk-auart.

How can i create a CUSTOMIZE multiple selection like standard

selection-screen from SAP when we create a report.

For a better view on what i want:

This text field already use F4 customize search help. I need a multiple

selection lines (like standard

selection-screen a button on the right side of select-options field).

Remember, i don't create textfield from select-options (e.q. SELECT-OPTIONS

s-auart)

Please guide me.