How can i Root an cat b15q?
The only thing i found on the web was rootgenius, but it failed rooting the device.
The b15q shows up as mt6582.
Any suggestion or solution?
May I suggest you take a look at this thread: [UTIL][WIN][MT65xx] MTK Droid Root & Tools | MediaTek Android Smartphone
It says it is for MT65XX and since yours is MT6582 you may have some luck, do ask in the thread if you have any issues.
TowelRoot is also a very generic root that works on a lot of devices and may be worth having a look at here: TowelRoot