A number of mobile operator provided devices are shipped without the Windows Live services available. There is now a version of Microsoft‘s Windows Live for Windows Mobile, without Messenger that is available as a free download at http://wl.windowsmobile.com.
While most Windows Mobile 6 devices ship with the full version (with Messenger), some mobile operators prefer to ship one of our partner-developed Windows Live Messenger clients on their Windows Mobile 6 handsets. To ensure all users can receive the advantages of push Hotmail access, Windows Live Contacts synchronization, a Live Search bar for their homescreen and one-click photo upload to Windows Live Spaces we have made the client available immediately. There is no charge for this client (or the services supported by it) apart from any operator data charges.
You can download it from HERE