Thanks for firmware. I was able to flash it on MiFi router.
I had to compile QFirehose on PC using openwrt cross compile for mips 24kc arch.
After it I had to connect USB drive and make extroot, because firmware was too big for MiFi flash.
Flashed succesfully and new version is visible in webgui.
Another option is to buy mini PCIE adapter and flash it on PC.