Sometimes you just don't have ssh access to your server ;) This is where web based applications come in really handy. There are a few web frontends for rtorrent. See here
I'm not going to go into detail on how to setup rtorrent or apache, only how to setup for the guis.
Install the apps:
Emerge rtorrent with xmlrpc enabled:
net-p2p/rtorrent-0.8.6-r1 USE="ipv6 xmlrpc -daemon -debug"
Emerge the scgi apache module:
www-apache/mod_scgi-1.13
Emerge xmlrpc
dev-java/xmlrpc-2.0.1 USE="-doc -examples -source -test"
Configure:
APACHE:
Add "-D SCGI" to APACHE2_OPTS in /etc/conf.d/apache2
Add "LoadModule scgi_module modules/mod_scgi.so" to /etc/apache2/httpd.conf
Add "SCGIMount /RPC2 127.0.0.1:5000" in the <VirtualHost _default_:443> of /etc/apache2/vhosts.d/00_default_ssl_vhost.conf (you can also this for non ssl if security is not an issue)
RTORRENT:
Add "scgi_port = localhost:5000" to your ~/.rtorrent.rc file
That should be the ground work for most frontends as rtorrent only uses XMLRPC.