If Hal is set up to start up when the computer starts up, Hal should be inside the system tray over near the clock and not visible on the desktop. If this is so and one has an Icon to the exe on the desktop like Previously gave directions for, all one has to do is click the icon to display Hal on the desktop.
If Ones Hal is set to not start up when the pc starts up, one would have to click the icon let Hal load to the system tray, and once Hal is loaded they could click the desktop icon again to have him visible on the desktop.
The way I have my Hal set up is to start up when the pc starts, I then have a batch file that starts with the pc as well and make Hal visible once he enters the system tray. I then use voice control to hide or display him any time afterwards. I have put the batch file within a forum post here. A search for batch files should do the trick if one wants it.
I also use Rainmeter a couple of years ago, and created a toggle button to display Hal or send him back to the system tray.