To use SLaTeX as a standalone program, either drag your ".tex" file onto SLaTeX (on Windows or MacOS X), or type slatex file in a command shell.
NOTE: If you compile your ".tex" file without using slatex (i.e., by using slatex -n and then using latex directly), then your TEXINPUTS environment variable must contain a reference to the directory in which the most recent version of "slatex.sty" lives. That file resides by default in the "slatex" collection of the main installation.
In addition to the SLaTeX tools, this collection contains a parallel set of PDF-SLaTeX tools, which are identical except that they call pdf-latex rather than latex. In particular, there is now a launcher called (PDF-SLaTeX/pdf-slatex).