Before you connect your printer software, make sure the printer is ready.  Plug the printer in to a power source.  Install fresh ink cartridges, toner and paper if necessary.  Make sure your printer is connected to your computer. Software Update will search for the latest OS updates, including new printer software.   Updating your software before adding the printer will give you the best chance of locating the correct software.  Go to the Apple Menu and choose Software Update.  Enter your login and password if necessary. The App Store will open. A list of available updates will appear.  Any OS X updates will appear at the top of the list. Click Update All to download all updates, or choose the updates individually. Updating your software in Lion is simple.  From the Apple Menu, choose Software Update.  The Software Update window will open. Select the items you want to install. Click Install. In this step, you will install the printer driver manually.  Follow these steps:  From the Apple Menu, click System Preferences. Select View, then Print & Scan. If you are prompted to do so, enter your login and password. Click and hold the + (plus sign) button.  From the pop-up menu, choose Add Other Printer or Scanner.  The Add Printer window will open. In the Add Printer window, click the icon that says Default.  A list of printers will appear.  Find your new printer on the list and select it.  Click Add, and your printer will be added.

Summary:
Prep your printer. Run a Software Update (Mountain Lion). Run a Software Update (Lion). Add the printer manually.