Click the Sirius link on the upper-right-hand corner of the PlanetLab website.
Select your slice name from the pull-down menu.
Select “ASAP” (As Soon As Possible) if you would like to sign up for the earliest time that appears in green below. Otherwise, select “Specific Time”.
If you chose “Specific Time” in the previous step, click on the time that you want.
Your reservation now appears on the list, and the time you chose is now red.
Contact David Eisenstat (deisenst AT cs DOT princeton DOT edu).