hi Jerry
this is done in the following way:

on the pickfield control
change the luserPreparePickData to .T.
change the lWorkOnView to .T.
change the nValidMode to 2 && user validation

in the preparePickData method enter the following code
lparameters tcCursorName
select (your select statement) into cursor ( tcCursorName )

in the doUserValid method enter he following code
lparameters tcCursorName
select (your select statement) + this.txtField.value = (fieldExpr) into cursor ( tcCursorName )
return _tally > 0


hope it helps,
Nir.