Howto sort the result of UNION (without modifying its type)?

Hi,

I have a query where I UNION several select statements which return
IDs of type INTEGER.
This works well, if the IDs don't need to be sorted:
> SELECT id FROM table WHERE id IN ((select id FROM table WHERE ...) UNION (SELECT id  FROM table_ WHERE ....))


However I need the result the UNIONs to be sorted, so I tried the following:

> SELECT id FROM table WHERE id IN (SELECT col0 FROM ((select id FROM table WHERE ...) UNION (SELECT id  FROM table_
WHERE....)) AS col0 ORDER BY col0 OFFSET X LIMIT Y) 
FEHLER:  Operator existiert nicht: integer = record
ERROR: Operator does not exist: integer = record
LINE 1: Select id FROM table WHERE id IN (Select col0 FROM ...

Is there any way to get the results of UNIONs sorted, without
converting it to record?

Thanks, Clemens

PS: I know the query looks really stupid, however the queries I UNION
are auto-generated SQL.
I don't have much choice here to write the query more efficient :/