Userscripts.org

Firefox + Linux:

path=~/.mozilla/firefox
cd $path/`ls $path | grep -E '[[:alnum:]]{8}\.[^ini]'`/gm_scripts/amo_-_skip_to_install/
grep -c -P '^(?!(\/\/))[^\;\n]*?(if|function|;)[^\;\n]*' *
cd

Songbird + Linux:

path=~/.songbird2
cd $path/`ls $path | grep -E '[[:alnum:]]{8}\.[^ini]'`/gm_scripts/amo_-_skip_to_install/
grep -c -P '^(?!(\/\/))[^\;\n]*?(if|function|;)[^\;\n]*' *
cd

NOTE: This isn't a universal line counter, as you can see it only works for this script.

Other Platforms will hopefully be supported, please suggest methods below.