suggestion:
create a file to save the texts.

So well with the plugin SignLink: http://dev.bukkit.org/server-mods/signlink/
The signs could load the texts, the classic form, not as in SignLink, where the text is a sing to another.
sample file:
texts:
'1 ':
line1: &1this
line2: &2&lcoool
line3: * form *
line4: edit sign
'2 ':
line1: [cmd]
line2: &2&lcoool
line3: * form *
line4: edit commands

So in the game, the admin could just load the text typing something on the board:
eg

/signedit [id]

and the plate would load the text.

This would be a form, to edit a large number of signs, at the same time, anywhere, without the need of being logged.

Suffice it to load at startup
when the server was started
eg
I would make a tutorial area, with many signs
but instead of editing out one by one, as in the classical manner.

I would edit the text in config.yml file.
type into the console magicsings reload.
and within the server I put the signs with texts previously configured in file, as its id.