somehow, they are going to need to enter a value, either a list of things to keep or to exclude. It can be delimited, so you might say list the states, and another option to be included or excluded.
so you might get list like az, ca, tx as long as you know the delimiter, or the items are unique, you can put that in the record selection criteria, along with the include/exclude flag.
Something like:
if @include then
(instr(@list, {table.field}) > 0) //is true if in the list
else
not (instr(@list, {table.field} > 0) //return false if in the list
HTH