How do I get into boot options with a non-mac keyboard? I boot my mac mini, hold down alt on my non-mac keyboard, but it does not go to boot options.

How do I get to boot options with a non-mac keyboard then?
Things which seem to work:

Mac mini late 2012: I had to plug the keyboard into the USB port closest to the middle, then it worked.
MacMini (mid-2010): the outside USB port worked for me with an ancient Microsoft intellitype keyboard. I also unplugged the USB mouse receiver, so that the only USB input was the keyboard. That seemed to make the difference and let me into the boot menu options.