As far as I know option buttons do not have a multiselect option.
You have to use multiple checkboxes and check against their values. You can
offcourse mimmic Option box layout by placing a rectangle around them.
To make checking of the values easier you could call them check1..checkx, so
that you can loop through them & check their checked status
you can even build your own class and mimmic the listbox multiselect through
that.