polish dvorak keyboard map for mac
Simply copy dvorak_pl.keylayout to your 'Keyboard Layouts' directory
$ cp dvorak_pl.keylayout ~/Library/Keyboard\ Layouts/
Or make this layout available for all users of your mac by coping it to global 'Keyboard Layouts' directory
$ sudo cp dvorak_pl.keylayout /Library/Keyboard\ Layouts/
Now you should be able to see, and use, this layout in 'System Preferences -> Language & Text -> Input Sources'.