SE P900 update , how to ?

Hello , the P900 is not available anymore in the official website so im having trouble since the SE Update Servicedoes not work anymore .
I need to update an old SE P900 using the P900_R3D011_Upgrade-Debrand_Firmware_avravailable on the Firmware downlaod section of the forum , and install the french language , or even re-flash my phone,
now im not sure of the sofware that i should use for that task ,
is it a version XS++ or a version Se_Tool that i need ? My mind is not clear about the process...

Regards.