Your best bet is to update to 4.1 (using waninkokos installer) then install preloader and use the hacks to block updates. Before doing any of this, you should install bootmii (as boot2 if possible) and run a backup of your NAND. There are plenty of threads available for this, just do a search for bootmii and you should find many discussions about it. Make sure to select "search entire post" as only titles are searched by default.