Looking at /etc/e-smith/templates/etc/fetchmail/50multi-drop, it looks as though you can specify SSL by:
config setprop fetchmail SSL enabled
expand-template /etc/fetchmail
According to 'man fetchmail', specifying SSL will cause fetchmail to use the standard port for the secure version of the specified protocol (IMAP -> IMAPs, so presumably also POP3 -> POP3s)
If true, you should only need to configure the gmail settings in server-manager, then manually issue the two commands shown above.
I don't have the fetchmail contrib loaded, so I can't help with that.