I was in your boat. Had no computer back when I rooted (fortunately, fastRX8 made a tutorial how to do it without a computer at all, and I'm forever grateful), but that was Eclair and before revolutionary or even unrevoked bacame necessary.
That said, it seems like Captain Throwbacks thread on mikmik forum about downgrading would work for you (from the bit that I've read), so don't completely give up hope. Earlier post linked to a thread, which I believe also has a link to Captains thread at mikmik.
I'll look for more direct link, gimme a minute.
Also, if there's anyone here who is probably most experienced to help, it would, without doubt, be Captain_Throwback, in case you might wanna PM him.
Edit: link doesn't look live. If you quote it, it should go live.
Sent from my PC36100 using xda premium