Summarize this article:

This is much different than syncing in the standard mode and is not permanent.  One-Time Mode synchronization lets you use your remote on a different Wii console (say a friend's) or a different remote on your console. You can also use it to change the order of players without turning off the Wii and starting over. This does not get rid of the settings in Standard Mode. Once you turn the power off, the settings used in One-Time Mode will go away, never to return. If you accidentally turn the power off, you will have to start the process all over again, as your Standard settings have taken effect. Be sure you're using a Wii remote that is synchronized with the Wii console you're currently using. Make sure both the console and the remote are on and working. Your other options are "Wii Menu," "Operations Guide," "Reset," and "Close." This is also where you change the volume and rumble. It's only temporary. If you're syncing to someone else's console, your remote will unsync when the power is turned off. Important: Use the Wii remote that you want to synchronize with the console. Should be a no-brainer, but you never know.  The Player LED will blink during the syncing process. When the blinking stops, the connection is complete. If you are syncing multiple Wii Remotes, press the 1 and 2 Buttons on the Wii Remote you want to be player 1. Immediately after (without a significant pause), press the 1 and 2 buttons on the remote you want to be player 2. The order in which you push the buttons determines the order of the players in multiplayer games.

Summary:
Know the purpose of one-time mode synchronization. Press the HOME button. Select the Wii Remote Settings option from the Home Button menu. Select the Reconnect option. Press the 1 and 2 Buttons at the same time.