retrieving parts of a resultset

I want to create a program which displays large tables and makes this possible
over a slow connection. The problem is that when i do a PQexec the entire
retultset is transfered. 

I would like to make pqsql process the query but only tranfer the the rows i 
ask for when i ask for them. This way i could transfer just the information 
currently displayed and not the entire result. 

Is this possible or do i have to do a (create temp table as select ...) and 
then do (select ... limit ..) in this temporary table? 
This would work but i dont think it's a very good solution. 

 / Christoffer Gurell