You have basically two options: Put a second field on the layout, or put a Script Trigger on the field to cause the record to be committed when a selection is made.
Edit: Oops - missed the part about Find mode. You'll need the second field, or the Script Trigger will need to go ahead and perform some other operation (like performing the Find).
Wouldn't an OnObjectModify script trigger be all you'd need?
Yes, provided the script did something to get the focus off the field; otherwise, the value list still comes up.
That works great. I ended up using a go to field without specifying a field along with the modify script trigger.