Yes.
Steps:
1: Open libs/ldaplib/attrs.py, add 'jabber' (or whatever you want) in below two lists:
USER_ENABLED_SERVICE = ['jabber', ]
USER_SERVICE_UNDER_CONTROL = ['jabber', ...]
2: Open libs/ldaplib/iredldif.py, find line 160, in function "ldif_mailuser", append 'jabber':
('enabledService', ['mail', 'smtp', 'deliver', 'jabber',
3: Open templates/default/macros.html, find line 360, in macro "display_enabled_services", append 'jabber':
{#
# We already have below lines
#}
<div class="mf-item">
<span class="fld-input"><input type="checkbox" name="enabledService" value="managesievesecured" {% if 'managesievesecured' in enabledService %}checked{%endif%}/></span>
<label>{{ _('Customize mail filter rule over TLS/SSL.') }}</label>
</div>
{# Append 'jabber' #}
<div class="mf-item">
<span class="fld-input"><input type="checkbox" name="enabledService" value="jabber" {% if 'jabber' in enabledService %}checked{%endif%}/></span>
<label>{{ _('Jabber service.') }}</label>
</div>