Seaside FAQ: Change The Configuration Application Username And Password

To read:

(WADispatcher default entryPoints at: 'config') preferenceAt: #login.
(WADispatcher default entryPoints at: 'config') preferenceAt: #password.

and to change:

(WADispatcher default entryPoints at: 'config') preferenceAt: #login put: 'new id'.
(WADispatcher default entryPoints at: 'config') preferenceAt: #password put: 'new password'.

-courtesy of Michel Bany