I managed to use my SPP-2040 under 10.4.7 with
1- with the Printer Utility, ask Printer Utility > Re-init Printer Utility (this cleans the previous installed drivers)
2- donwload and install the cups 1.2.3 from
http://www.cups.org/ Common Unix Printing Service
3- install the driver supplied by Samsung and voilà! It works.
Some tweaks are needed since the Post format has a white border: try the PostBord which is full page. Colors seem a little dark so trim the colors before.
As always, a full backup could be safe. I have experienced no problem since this implementation.
Best regards from France,
iMac G5 iSight Mac OS X (10.4.7)