Rails/redmine installation on debian etch as a user requires a bit of googling. This is what I have done.

First, as root, install these packages:

apt-get install ruby rake
apt-get install rubygems -t etch-backports
aptitude install libopenssl-ruby1.8 libfcgi-ruby1.8

you need the backports version of gems as the version in etch is not compatible anymore with redmine.

Then you should follow these instructions: http://www.redmine.org/wiki/redmine/HowTo_Install_Redmine_in_a_home_directory_on_Debian

Once you setup the db, installed your gems (remember to install rails 2.0.2 : gem install -i $GEM_PATH -v=2.0.2 rails -y) you need to pass your GEM_PATH to your cgi. I use fcgi and I added ENV["GEM_HOME"] = "/path/to/gems" to the file dispatch.fcgi .

that’s all. Happy redmining