The main distribution and discussion site for Slash is Slashcode. However, the InstallSlash site provides some good instructions, and the Slash IRC channel is home to a number of prominent Slash developers.
O'Reilly and Associates published a book on Slash, Running Weblogs with Slash, by Chromatic, Brain Aker and Dave Krieger. I have not read this book, but the sample chapter available on the O'Reilly Web site, as well as the table of contents, indicate that it may be a useful purchase, particularly for system administrators less experienced with Apache and mod_perl.
If you need help compiling or installing mod_perl, be sure to consult the mod_perl guide, compiled and edited by Stas Bekman. The guide has grown greatly over the years, and it now contains a great deal of wisdom about the installation, care and administration of a mod_perl site.
Slash: www.slashcode.com
InstallSlash: installslash.org
Slash IRC channel: #slash on irc.slashnet.org: irc.slashnet.org/channels/slash
Running Weblogs with Slash: www.oreilly.com/catalog/runblogslash
mod_perl guide: perl.apache.org/guide