I found this in a few different places around the 'net - hopefully it's helpful:
Obtain Remote Assistance Using Windows Messenger in Windows XP
This step-by-step article describes how to use Windows Messenger to obtain help using the Remote Assistance feature in Windows XP. Remote Assistance enables you to allow another user to make a remote connection to your computer, which they can use to view your computer screen, participate in real-time chat and, with your permission, remotely control your computer.
Requirements Both the local and the remote computer must be using either Windows Messenger or a Messaging Application Programming Interface (MAPI)-compliant e-mail program such as Microsoft Outlook or Outlook Express. Both computers must be connected to the Internet while using Remote Assistance.
Note: If your computer is behind a firewall, you may need to reconfigure the firewall to allow Remote Assistance. Contact your network administrator before using Remote Assistance.
To obtain help using Remote Assistance:
- Connect to the Internet, and then sign in to Windows Messenger.
- Click Start, and then click Help and Support.
- Under Ask for assistance, click Invite a friend to connect to your computer with Remote Assistance.
- Under Remote Assistance, click Invite someone to help you.
- Under Use Windows Messenger, click the contact that you want to invite, and then click Invite this person. Note: The contact that you want to invite must be online.
You receive the following message, where Assistant is the name of the assistant that you invited:
Inviting Assistant to connect to your computer. Please wait for a response...
Invitation is accepted...
- After the remote assistant accepts your invitation, click Yes when you receive the following message:
Assistant has accepted your Remote Assistance invitation and is ready to
connect to your computer.
Do you want to let this person view your screen and chat with you?
- If the remote assistant wants to remotely control the computer, click Yes to accept the request when you receive the following message, where Assistant is the name of the remote assistant:
Assistant would like to share control of your computer to help solve the problem.
Do you wish to let Assistant share control of your computer? The remote assistant can now control your computer remotely. This includes the ability to shut down the computer.
Note: Do not use the mouse while the remote assistant controls the computer.