Using manual registration in a gerrit plugin

Using manual registration in a gerrit plugin

When writing gerrit plugins you have the choice to either use
AutoRegistration (using the @Listen and @Export annotations) or to use
manual registration by defining <GerritModule>, <Gerrit-SshModule> and/or
<Gerrit-HttpModule> in the pom.xml.
Auto-Registration is shown in this slide set, but documentation on how to
use manual registration is sparse. So how is it done?