[arch-general] Starting gpg-agent on X login (gdm)

After looking through my new shine Arch system I found that ssh-agent is run from /etc/gdm/Xsession, so I suppose that's where I need to make changes in order to get gpg-agent to run, right? Is there some documentation on the preferred way of doing this? Should I look into using seahorse instead of {ssh,gpg}-agent? /M