prs t1 firmware downgrade

Hi,

Thanks in advance for reading this. I bought a PRS T1 on ebay recently, thought I would do the right thing and install the latest firmware 1.0.07.05070.
That went well then looked around to do a root and install some tweaks, especially text to speech.
Problem, looks like the rooting procedures do not support this firmware.
Decided to stop before I did any more damage : <
Question, is it possible to back this firmware update out or over-install something that would allow me to root and do the tweaks.

Regards,

Tony