Well, I don't think I'm really 'good' enough yet to write up a guide or anything, since I'm kind of in the same boat as you. Although, I wasn't quite as frightened of the talents as you from what it sounds :). But it truly is a completely different mindset between the two specs. The main purpose for disc now (at least in my opinion) is survivability. The talent spec I ended up going with is: http://www.wowhead.com/?talent=bVhbuhxtbcsVcRtbx
I just focused on the synergy with the shield talents and things that would help me live longer in a PvP situation. Although, the things that really make disc great are Penance, Rapture and Divine Aegis. As far as how to play them goes....I'd recommend taking a similar spec and just diving into BGs head first. It'll suck at first, and switching between healing and DPS will be difficult, I'm still having trouble wrapping my head around that concept. I mostly find myself running around, shielding people taking spiky damage, renewing pretty much anyone < 80% health, casting prayer of mending every time cool-down is up (in combat, of course), using penance for healing (especially big heals) when possible, flash heal to pick up the slack and doing DPS type stuff when healing isn't really needed. It's also useful (or vital) to use raid frames that'll let you know when people are in range or not.
You should give it a try. It's really not that difficult. And if it sucks and doesn't work out you can always spec back. Use this opportunity to try out different specs because that's pretty much what this patch is for - letting us experiment with the new talents before the expansion so we have an idea of what we want to do before it's released.