If you are printing reports generated through Discoverer, you should be able to print to any printer you can use with other desktop applications.
Printing done from the Oracle toolbar and Print Action on various Oracle forms also uses the locally defined printers.
For best results these need to be Postscript printers. The solution to any problem reports for printing to non-postscript printers will result in a suggestion to upgrade to a postscript printer.
To use Oracle defined standards reports your printer needs to be defined to Oracle. This is a two-step process which needs to be performed by someone with Printer Setup Specialist responsibilities in Oracle (check with your ISP Area Advisor or LSP to determine who is your Printer Setup Specialist if it isn't you.)
To have a default system printer for Oracle established for your account you need to contact the ITC Computing Help Desk (924-3731) with your Oracle ID and the Oracle name of the printer you want as your default printer.