HP 2420 - Manual (Page 309)

In the hp LaserJet Installers folder, double-click the installer icon for the language you want to use.
This begins the install process.
When you run the installer you might first see the Authenticate dialog box (OS X V10.1 and later
only).
Figure 6-12 Authenticate dialog box
Enter the correct password and click OK to continue. The install splash screen appears.
Figure 6-13 HP LaserJet for Macintosh installer splash screen dialog box
Click Continue. The software License dialog box appears.
Macintosh 293
Non-Windows
installation