NOTE: This article shows how to setup a Bluetooth Keyboard, however it should also be possible to use these steps to enable the soft keyboard and avoid the need for a physical keyboard at all.
Recently I was tearing my hair out trying to figure out how to do this and every forum thread I came across claimed it was impossible. The problem is that when you intially boot the mini, it will detect a bluetooth mouse but for whatever reason *will not* detect a bluetooth keyboard. Once you get to the initial account creation screen, a keyboard is required to enter a name and password, otherwise you cant proceed.
I came across a method for setting up OSX Server headlessly with VNC, but since I wasnt running Server it didnt help. After reading through what I could find through Google searches, I decided to do some experimentation of my own.
My first first idea was to try and copy text from wherever I could find copy-able text and then past that into the name / password fields. I did find some copy-able text on the error dialog that appears after attempting to submit the empy account /password form, but to my dismay, I discovered that the paste option was disabled for input fields.
My next idea was to try and plug in a headset and use the text to speech options that come up when you right click the form input fields. Unfortunately, even with a headset plugged in these options never lit up. While I was idly clicking around, I noticed a Substitutions option:
Inside the resulting dialog was a Text Preferences button which took me to the Text Preferences section of System Preferences:
If you look closely, you’ll see a back arrow in the top left corner of the screen, which will take you to the main System Preferences screen. From there, its a simple matter of going to the keyboard section and adding a bluetooth keyboard. Success!