I keep getting asked this so I just decided to make a quick tutorial.

All you need to do is download http://en.garenatotal.com/index.php and install it.

This is what it looks like.Simply click on Warcraft hotkeys and set your desired hotkeys by clicking on the desired slot and then pressing the button that will be the hotkey to this slot.

It will automatically start Garena if you have it.If you don't want to use it with Garena just close the client and start your Warcraft.

If you want to use the Auto Join function just select a room , hover over it with your mouse and press F8.
If you want to try to join multiple rooms at the same time press F7 and select the rooms you want to try to join dragging down or up then pressing LMB (left mouse button).