Download from Nvidia developer site Ventana Development Kit for ICS (Tegra2) and you'll get everything you need for nvflash include drivers. For tutorials how to use nvflash you need to find out yourself. XDA has lot of them, wikipedia too.
I did a little stuff, mostly download from phone to pc and not all commands working.
i have recovery.img, boot.img,system.img but i'm unable to create flashable update.zip with sistem that will boot properly. allways stuck on boot logo and keep reseting. there is no bootloader so fastboot options not working. keep saying waiting for device becouse cant boot to bootloader to make flash. is there any other options besides update.zip, fastboot to flash those img?