Typing Mac OS X v. 10.4
Open the Apple menu,
Select System Preferences and select International.
Select Input Menu.
Select the checkbox next to Hebrew-QWERTY and Greek Polytonic.
(note: to view the keyboard layout select Keyboard Viewer from the top of the list.)
Select the "Show Input menu in menu bar" checkbox.
(note: the default for switching between languages is Apple, option, space. This can be changed under "Input Menu Shortcuts" by clicking Keyboard Shortcuts...)
A small American flag should now appear on the menu bar. To change input methods manually click this icon and select the desired input method. To see the input method keyboard select Keyboard Viewer.