as i understand it, postgres doesn't yet support cursors. however, with the LIMIT and OFFSET modifiers in a SELECt you can get the same behaviour.
SELECT <fields> FROM <table> ORDER BY <field> LIMIT <recsPerPage> OFFSET <offset>
<fields> is the fields to select <table> is the table you're selecting from <recsPerPage> is an integer 1..n for the number of records per page. <offset> is calculated as ((page - 1) * recsPerPage) where the page number is 1..n
make sure you order your select by something, else the records in a page may not quite make sense.