The docs aren't very clear on how this is accomplished.  It looks like I'm 
doing $PATH correctly, and after that it looks like $MANPATH gets fixed up 
automatically because the manpath program figures out the correspondence 
of bin directories with man directories.

$INFOPATH is more obscure.  It looks like if I create $INFOPATH in the 
environment, it adds listed directories to the path for info, but info is 
finding more directories from some other source.  It also doesn't find 
info directories automatically by correspondence with bin directories 
listed in $PATH.

Google results are surprisingly unhelpful.  Any ideas?