The LaTeX (or TeX) file that is given to SLaTeX undergoes
some code-setting preprocessing and is then handed over to
LaTeX (or TeX). The style file slatex.sty defines
the appropriate commands so that LaTeX (or TeX) can
recognize the SLaTeX-specific directives and either process
or ignore them. You may either \input the file
slatex.sty as usual, or use it as the
\documentstyle option slatex.
The default database of SLaTeX recognizes the keywords of Scheme.
If you're using Common Lisp, use cltl.sty rather than
slatex.sty. cltl.sty loads slatex.sty
and modifies the database to reflect Common Lisp. You may
fashion your own .sty files on the model of
cltl.sty.