I read stemp1ar's question differently. I think he wants a subset of (val1, val2, ...) consisting of values not found in the table. For example, val3, val8, and val13 are in the list, but not represented in the table. Stemp1ar wants a query that returns val3, val8, and val13. The "not in" syntax won't help here.
Offhand, I can't think of a particularly good way of doing this. If you are willing to go to the overhead of creating a second table, say "list_values", to store the possible values, you could do something like this
select list_item from list_values
where list_item not in
(select col1 from your_table
where col1 in (val1, val2, val3, ...))