First of all, downgrade from Habib
4.66 to
3.55 using the Rogero Downgrader. Click here to download it:
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Be sure to check if you have the QA Flags enabled before downgrading.
Once done and being at
3.55, you can install any Custom Firmware you want.
Here's the link for Rebug REX 4.65.2 (assuming you'll be on CEX, otherwise go for Rebug D-REX edition):
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Have a nice day man!

You can install both things through the XMB menu without a problem.