LaTeX: Specifying default document-wide font

For some fonts, it's easy to replace the default font with something like: \renewcommand{\rmdefault}{somefont}.

However, some fonts, like BrushScriptX want you to use a special command like \bsifamily to use the font. In the

\bsifamily is defined in /usr/share/texmf-texlive/tex/latex/brushscr/pbsi.sty:

\DeclareRobu开发者_如何转开发stCommand\bsifamily{\fontencoding{T1}\fontfamily{pbsi}%
  \fontseries{xl}\fontshape{n}\selectfont}

In this case, I have a document that uses a cls stylesheet that I am editing. I'm using the standard includes to use this font:

\usepackage[T1]{fontenc}
\usepackage{pbsi}

If I try to use \renewcommand{\rmdefault}{bpsi} in my document's template, it fails with the error: Font shape `T1/pbsi/m/n' undefined

What might be the best way to replace the default roman font with BrushScriptX in a template, like \renewcommand{\rmdefault}{otherfont} would?

If you look inside pbsi.sty you'll find

\DeclareRobustCommand\bsifamily{\fontencoding{T1}\fontfamily{pbsi}%
  \fontseries{xl}\fontshape{n}\selectfont}

Therefore, to set this font as the default — ugh :) — you'll need to write

\renewcommand\rmdefault{pbsi}
\renewcommand\mddefault{xl}

(\mddefault is the default "non-bold" series used in running text.)