Comment # 14 on bug 819066 from Dennis Olsson

Closed, because no one seems interested in solving this and because it is of no
interest any more anyway.

As a side note, I would like to mention that I solved my problem by not using
any of the X11 scripts at all, but instead by adding 2 program entries to the
"Desktop File" menu used to automatically start up programs with KDE.
The "Desktop File" menu is found under:

    "System Settings" -> "Startup and Shutdown" -> "Desktop File"

and by using
    "Add Program...",

twice, I added two entries named "ssh-add" and "ssh-add ~/.ssh/<private key>",
which ensures that the default private key file "~/.ssh/id_rsa" and the
arbitrary private key file "~/.ssh/<private key>" are added to the ssh-agent
daemon after entering the pass-phrase in the pop-up windows that appears after
login to the KDE desktop.