Well it seams that you can figure out how to downgrade.
There have been many downgraders in after 2.5, use whatever one you feel comfortable with.
Pandora battery is for downgrading, so if you can get to 1.50 without it, which you can, you don't need it.
After you're on 1.50, you need to upgrade 3.52 m33 > 3.52 m33-4 > 5.00 m33 > 5.00 m33-6
Here is a pack that I put together with all the upgrade files you'll need.