The main distribution and discussion site for Slash is www.slashcode.com. However, the InstallSlash site (installslash.org) provides some good instructions, and the Slash IRC channel (#slash on irc.slashcode.com) is home to a number of prominent Slash developers.
O'Reilly and Associates publishes a book on Slash, Running Weblogs with Slash. 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 who are less experienced with Apache and mod_perl.
If you need help compiling or installing mod_perl, be sure to consult the mod_perl guide, edited by Stas Bekman, at perl.apache.org/guide. The guide has grown a lot over the years, and it now contains a great deal of wisdom about the installation, care and administration of a mod_perl site.