The 3.5 SRD has the following to say about Slippers of Spider Climbing:
"Slippers of Spider Climbing: When worn, a pair of these slippers enable movement on vertical surfaces or even upside down along ceilings, leaving the wearer’s hands free. Her speed is 20 feet. Severely slippery surfaces—icy, oiled, or greased surfaces— make these slippers useless. The slippers can be used for 10 minutes per day, split up as the wearer chooses."
Does this mean that the wearer can activate/deactivate them as a free action?
"Slippers of Spider Climbing: When worn, a pair of these slippers enable movement on vertical surfaces or even upside down along ceilings, leaving the wearer’s hands free. Her speed is 20 feet. Severely slippery surfaces—icy, oiled, or greased surfaces— make these slippers useless. The slippers can be used for 10 minutes per day, split up as the wearer chooses."
Does this mean that the wearer can activate/deactivate them as a free action?