Installed with cpan, for some unknown reason (to me ;-) the prerquisites were not automatically satisfied with cpan:

Start cpan
cpan
make sure that the "follow prerequistes" option is on:
o conf init

install inc::Module::Install
install IO::All
install Archive::Tar
and any other "prerequisites" in Makefile.pl from the archive that cause problems.

then
install WWW::Streamripper::WebUI

(from README)
change to www html directory (e.g. /var/www/)
mkdir streamripper
cd streamripper
perl -MWWW::Streamripper::WebUI -e 'install'
(end of from README)

If you use Apache, you need something like this:
----------------------
<Location /streamripper/>
SetHandler perl-script
PerlHandler ModPerl::Registry

# Fix for mod_perl bug, turn this on if you get an error in your browser
# ReWriteEngine on
# ReWriteRule ^/(.*/$) /$1index.html

Options +ExecCGI
PerlSendHeader On
Allow from all
</Location>
----------------------