adding passphrases to gpg-agent

[Jorge Almeida]

Isn't there some way to do for gpg-agent what ssh-add does for
ssh-agent?

I'm trying to use a unique gpg-agent listening at a standard socket.
Unless I'm missing something, the only way I have to provide passphrases
to gpg-agent is to try some job (signing something, or whatever) and
then give the passphrase when asked for it. But the pinentry-program
entry in gpg-agent.conf decides whether I'm supposed to be in an X
session or not. (BTW, pinentry-curses didn't work for me. But that's not
the real issue.)
Is there an alternative?
-- 
Jorge Almeida