Easiest way to do it, if KDE is giving you problems, is to do it through the CUPS web interface. Head to http://localhost:631
and click on Manage printers, then Add Printer. From there, fill in the text boxes, and on the Device selection, select "Windows Printer via SAMBA". On the next page, for the printer address, use the following format:
smb://<username>[:<password>]@<computer IP>/<printer name>
AFAIK, you need to put in the user name, but if there's no password, leave out that section (including the colon). That should do it.