The best thing to do if you do not want to screw in your sensors is to use a small amount of clear silicone caulk in conjunction with double sided tape.  You can do this by using double sided tape to stick up the sensor and then add a small bead of silicone caulk around the edges of the sensor.  The silicone will set and hold the sensors in place. Double sided tape alone would fail after a period of time, but the silicone ensures that the sensors stay up.