Sorry, I'm having a bit of difficulty envisioning precisely what you're describing there :-)
I suppose you could consider a version of Etap's Vertical Tiller? I always thought it was one of the dumber things I'd seen (the 'helm seat' behind the tiller in the pic below would appear to afford one of the more uncomfortable, tiring steering positions in all of Creation), but Charlie Doane certainly liked it ... Needless to say, they've never really caught on...
ETAP YACHTS: Surviving the 2012 Apocalypse (and Bankruptcy?)
seems like an overly complicated way to make a whipstaff, to me. let me try to describe it simpler.
most cable/chain set ups put a quadrant on the rudder post. this acts to replace the tiller. you can't just cut the tiller really short because it doesn't work too well, that way. it's complicated.
anyhow a quadrant is like a really short tiller. it is a handle that runs from the rudder shaft forwards. it has to be pulled in a side to side motion.
in order to do this, most cable set ups run the cables out to the sides of the boat, through blocks, and then back in to the blocks at the base of the pedestal.
the cable runs, from those blocks, up to the wheel.
what i am saying is to mount a T across the rudderpost that runs from side to side, instead of back to front like a tiller. also, unlike a tiller, it wouldn't just be on one side of the rudder post. it would extend equally to both sides.
the cables attach to the ends of this T fitting. they run directly forward to blocks at the base of the pedestal. then they run up to the wheel.
you replace a complicated quadrant fitting with a simple bar fitting. you lose a set of blocks. don't need them. it would take less room to run cables.
the reason you need to usea quadrant instead of just a really short tiller is that the end of the tiller moves on an arc. if a cable pulls directly to the side of the tiller, it loses it's steady pull at a certain point. the quadrant fixes this. there are other ways to fix that, too.
however, my idea wouldn't suffer from this problem because it doesn't need to pull the lever so far as the other system. you only turn the rudder so far.
basically, my idea would work like a norweigian push pull tiller...only with cable. although, the bottom idea, part B if you like, would use a solid connector and be much like the norweigian push pull tiller. but part B would need a vertical shaft, in the pedestal and gears at the top. more solid but more complex.
is that better? i could try to draw a diagram in paintbrush, if i am still too unclear, but i won't promist the quality of such a drawing!
i can't just draw it on paper and scan it in because i am snowed in at my girlfriend's house and she has no scanner.