3aa custom rom

I've browsed the threads and searched and can't find a for sure answer. Is it possible to flash a Rom like XDABBEB's by downgrading or any other relatively safe process if I'm on 3aa? I'm trying not to even soft brick because my home internet is very slow and it would possibly take me hours to download necessary files to recover from a soft brick. If it,is possible can you point me to where the directions are or help me out?

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