Oh my god !!! ( or maybe you prefer that i call you baudi ^^ )
I tried your tip with Titanium Backup, and this is perfectly working.
As you said, i've just converted Tasker into a system app using TB,
and then reboot my phone. ( Tasker crashed many time during the
process, and i had to reboot before the end of the process. I don't
know why, but the TB screen "please wait" was not disappearing. After
25mins, i decided to reboot. NB : I think i had to desactivate Tasker
before running TB, thing that i recommend to do. )
Then i created a test task, activating on a trigger SMS, which send me
back by SMS the phone Gps position.
Thanks, thanks, thanks, and thanks again !! Really helpfull !