The way I read your post, something is not making sense. Lets start by identifying exactly what you are replacing, then we can figure out the best way to put it where it goes.
Look at this Pelican Parts Tech Article:
https://www.pelicanparts.com/techarticles/Boxster_Tech/26-FUEL-Engine_Sensors/26-FUEL-Engine_Sensors.htm
The coolant temp sensor goes on the "belt" side (front) of the engine and does not require removal of the intake.
The oil temp & level sensor has a long probe attached and *does* go on top of the engine under the intake.
Answer me that and we can proceed if you still need help.