Fonts & Character Sets ⇒ Change the font to a titleformat defintion

[tush]

I want to customize the typeface for chapters and sections in the settings of a .def file.
My question is, how do I that?
For example, this is the subsection style as it is now:

Code: Select all

\titleformat{\subsection}%
  [hang]% shape
  {\fontfamily{palatino}\normalfont\large}% format applied to label+text
  {\thesubsection}% label
  {1em}% horizontal separation between label and title body
  {}% before the title body
  []% after the title body

I guess that that this is syntax on row 3 is probably incorrect.
Should I load a package for the use of the palatino font? If yes, then where inside the .def file?
I see here a complete list.
How do I use an arbitrary one of those typefaces?