Microsoft Knowledge Base Article 314381 contains the following summary:
This article describes how to configure a wireless or mobile device to receive instant messages from your online contacts
in Windows Messenger. The devices that this article applies to include Web-enabled cellular phones, pagers,
Microsoft Windows CE-based devices, and Palm OS-based devices.
To receive instant messages from Windows Messenger on your mobile device, you must install MSN Add-In for Windows Messenger and set up an MSN Mobile account.
Installing MSN Add-In for Windows MessengerFor additional information, click the article number below to view the article in the Microsoft Knowledge Base:
314353 Description of the MSN Add-In for Windows Messenger
In Windows Messenger 4.6, click Add-In Web Site on the Tools menu, and then follow the instructions on the Web site to install the MSN Add-In for Windows Messenger.