set :default_run_options, :pty => true
set :application, "test"
set :repository, "http://svn.example.com/test/trunk"
set :user, "hoge"
set :app, "example.com"
set :deploy_to, "/var/www/test"

role :my, "example.com"

task :deploy, :roles => :my do
    sudo "svn --quiet co #{repository} #{deploy_to}"
end

こんな風に書いたりすればなんとかできるっぽい(sudo権限が無くても配置できる所だったらsudoじゃなくてrunでも良い)