Marlin: go lower than 0 for z axis even when endstop is triggered

Hello,
I setted up a capacitive sensor for my printer, the problem is Marlin does not allow to go lower than 0 when the endstop is triggered, which is really not useful because the autobed leveling goes a bit useless.
I want to know if there is a way to go lower than 0 without being blocking by the message "endstops hit:...".
How can i set up Marlin for it ?
I already tried to change min_software_endstops to falseand i defined ENDSTOPS_ONLY_FOR_HOMING in Configuration_adv.h but nothing work
Someone could help me ?

You need to adjust the height of your endstop so that it triggers when the nozzle is one paper-thickness above the bed.

This is not the problem.
The problem is during the print it detect that it's at 0 so it does not go lower even if it's need after autoleveling...

*deleted*
-Olaf

Edited 1 time(s). Last edit at 09/12/2015 04:49AM by o_lampe.

Why do you want to go lower than 0?

By definition, 0 is when the nozzle is at the right height to print the bottom layer. If you go below 0, you won't be able to print. If you go below -0.3mm, your nozzle will crash into the bed.