Ive been asked COUNTLESS times, so here we go:
Downlod this file - http://rebug.me/download/4.30.2_D-REX_LINKS.rar
Okay, your on 4.21 Ps3ita (DEX) install that download via recovery mode and your rebug Dex 4.30.2. Go into rebug toolbox and swap your kernal, and your back on CEX.
Okay, for 4.41/4.46 ps3ita DEX users...
Download this file - http://rebug.me/download/4.46.1_D-REX_LINKS.rar
Once you've downloaded that file, go into recovery mode and install it... Now once your done, you will be on 4.46.1 Rebug Dex (D-REX). Go into your rebug toolbox, swap your LV2 kernal, now your on CEX.
If you wanted to, you could Downgrade back to Rebug 3.55 using the rebug 3.55.4 downgrader and install 4.21/4.30/4.41/4.46 REX Rebug CFW all over again.