Welcome to the forums,
su - zimbra
zmprov mcf zimbraXMPPEnabled TRUE
zmprov mc COSname zimbraFeatureIMEnabled TRUE
(COSname is 'default' unless you've specified others. Anything with zimbraPref is possible as an individual user setting that can override class of service when set explicitly on an account, if not set it just inherits the parent COS.)
zmprov mc COSname zimbraPrefIMAutoLogin TRUE
Might also:
zmprov mc COSname zimbraPrefIMNotifyPresence TRUE
zmprov mc COSname zimbraPrefIMNotifyStatus TRUE
zmprov mc COSname zimbraPrefIMReportIdle TRUE
Notifications:
zmprov mc COSname zimbraPrefIMFlashIcon TRUE
zmprov mc COSname zimbraPrefIMFlashTitle TRUE
zmprov mc COSname zimbraPrefIMSoundsEnabled TRUE
Then add a new buddy, after they accept you can click their name to chat.
I see you put ZCS5 in your profile but could you put in your exact version? (zmcontrol -v) And is this NE? (you'll also have easy YIM integration then)
You can also use external XMPP/Jabber clients:
Pidgin and Zimbra - Zimbra :: Wiki Spark and Zimbra - Zimbra :: Wiki Adium and Zimbra - Zimbra :: Wiki