Unfortunately even after creating a custom font there is still an issue using the icon mixin. Per the documentation you referenced you can either supply the icon mixin with two or three arguments, specifically three if you need to specify the iconCls name, icon character content, and font-family. However when compiling SASS you get an error that you cannot supply three arguments, and inspecting the mixin source supports this. Therefore it seems the only way to use custom font-family for icons is to modify the mixin source directly and change the name to character list. Since we all probably want to avoid modifying this source hopefully there is a fix in place for the final release of ST2.2 that allows you to specify all three arguments.