ah, you are right
at the moment plain-text is not supported.
but in next 2.3 build it will!
the format is a standard "base64".
my default text editor (pspad) knows how to encode and decode it.
anyway, you'd better wait for the next build.
since build #216 it will be possible to add a new account by just appending this text to the "accounts=" line
;login:myusername:mypassword