Obtain an adapter that connects your portable MP3 device through the cassette player of your 2006 Toyota Tacoma, such as the Griffin DirectDeck, Monster iCarPlay Universal, or any other similar adapter.
Put the 1/8-inch adapter plug into the headphone jack of your MP3 player, then put the cassette cartridge of the adapter into the cassette player of your Toyota Tacoma's stereo system.
Power up your MP3 player and play any song. Adjust the volume to about 75 percent of maximum. Note that you will not be able to hear the song quite yet.
Turn on your Toyota Tacoma's stereo system and adjust the volume of the stereo until you can hear the music playing from your MP3 player.
Obtain a car stereo adapter that will play your MP3 player's music by transmitting radio frequency (RF) signals through your Toyota Tacoma's stereo system, such as the Zune Car Pack, Griffin iTrip, or any other similar RF adapter.
Place the power plug of the RF adapter into the cigarette lighter socket (or 12-volt accessory socket) of your Toyota Tacoma, then place the connector of the adapter into your MP3 player as per instructions included with the adapter.
Turn on your MP3 player and play any song, adjusting the volume level to about 75 percent of maximum. Note that you will not be able to hear music at this time.
Engage the automatic seek function of your RF adapter, which allows it to automatically find an available FM channel through which your audio will be broadcast.
Tune your Toyota Tacoma's radio to the frequency displayed on the RF adapter, then adjust the volume on the stereo to a comfortable level.
Check out the owner's manual for the stereo system in your 2006 Toyota Tacoma to determine the preferred method for connecting a portable digital media player to the system's auxiliary input.
Purchase the appropriate cable that will connect your MP3 player to your Tacoma's stereo system, such as the Monster iCable 800 for iPod, Incipio OX Auxiliary Audio Cable for Zune, or other similar connecting cable as specified by the user's manual of your car stereo.
Connect the appropriate cable from your MP3 player to your Toyota Tacoma's stereo system's auxiliary input jack (often labeled "aux in," "line in, "MP3," etc.)
Enable the auxiliary input mode for your Toyota Tacoma's stereo system, then set the volume on your stereo about halfway between maximum and minimum.
Turn on your MP3 player and play a song, adjusting the volume to about 75 percent of maximum, then adjust the volume of your Tacoma's stereo system for maximum listening pleasure.