The keyboard layout that comes with Mac OS is strange to say the least. You have to press way to many keys to add the @ (alt + shift + 2) or the € (alt + shift + 5). And the square and curly brackets are in the wrong place if you migrated from a Windows layout. So somebody from a local apple comunity decided to make a proper one and I took it and tweaked a bit with Ukelele.
To add the new keyboard clone the repository on slo-keylayout on github, copy the
Slovensko (DE&AT).icns and
Slovensko (DE&AT).keylayout into
/Library/Keyboard Layouts/ (I used the system wide and not the user Library), then go into Settings → Language & Text → Input Sources and find Slovensko (DE/AT). I noticed that the new keyboard layout is not immediately taken into consideration despite selecting it, but all you need to do to make it work is to Logout and Login again.
Lets make it better
To make it even better fork the repository and tweek it some more. I’m sure somebody will thank you in the end.