Configure stunnel to run as a client, tell it to listen at a port (localport) of your choice, and tell it to connect to whatever irc-server you wish to use.
If you are unfamiliar with stunnel, a visit to
stunnel.org might be a good idea, as there are plenty of generic examples to work with, along with good documentations.
Configure eggdrop to connect to localhost:localport (that is, make sure it's the only server in the serverlist. Replace localport with whatever port you used with stunnel).