Simple really, there's a couple of ways:
1) Get a surgeon to graft some extra length onto your fingers (some more knuckles might be handy)
2) Buy an octopus and train it to do the job
3) Remove the dashboard and cut an access panel in the bulkhead
That probably doesn't help much, does it? [:o)]
To be honest, there are no really simple ways to do it, at least not that I've found. I did saw a combi spanner in half to create a couple of stubby spanners to tighten them down (works a treat), but that doesn't really help with starting the thread.
It's been about 18 months since I last did mine, but I seem to remember the job was a lot easier with the carbs removed - maybe more hassle than you want to get into, though?
I think there's nothing more to it than a lot of fiddling around, getting your hands in the right place, and patience.
(although if you have any children, you may find their small hands are perfect for the job! [;)])
Garry
1976 2.0 (soon to be 3.5!)FHC
http://reds-tr7.blogspot.com/