The Wireless Access Terminal is a handheld unit that lets you wirelessly access items inside your ME Storage from a distance of 16 blocks (expandable). It requires a ME Wireless Access Point to function. By putting Wireless Boosters inside the Wireless Access Point (Max = 16), you can expand it up to 32 blocks of distance.
It's a really great way to access your storage remotely, but will eventually run out of power. You can charge it in the ME Power Relay (Must be connected to the ME Network) or other machines like the Batbox, MFE, MFSU...
To Link it to your ME System, simply put it in the top slot on the right side of your ME Controller.