Okay, I'm aware this thread is long dead, but maybe this little bit of information may still serve some further readers in search of hints on easier 236B:4 input :) Unlikely, yet possible.
I use a plain unmodified X360 controller (it was easier for me, being a PS2 veteran and all, to adapt to its strange layout than to a totally different control concept behind arcade sticks). I'm a clumsy player, so I've developed an extremely weird technique to achieve a rather trivial result, I guess :) Anyway, that's how I get my iFC236B:4 on a more or less consistent basis, step by step:
1. Hold G. Do not release, it's not necessary, the following 236 input will register.
2. 236 with an analog stick.
3. A+B, mapped to L2 (or whatever it's called by Microsoft), which results in a B input in this particular case.
4. The moment the hit connects, press B face button and, immediately,
5. do a 4 with your stick.
Note on steps 4 and 5: B button resets the movement buffer to neutral (5). It's crucial, if you want your following 4 input to be reliable. Of course, you may press A or K, but B is much more convenient, since if you are anything like me (i. e., not a paragon of unerring motoric accuracy ;)), you'll eventually end up pressing that face button earlier then A+B. If that happens, there is a solid chance the game will still register the input the way you need: the face B will be your basic B after 236, while A+B will serve as a buffer reset button. Now, if you use A or K for buffer clearing, you'll get 236A's and 236K's in these circumstances, of course.
The results are quite satisfying. It's not a 100% 236B:4, but it's close to 100% 236B4, which is not bad in its own humble way :) Still wish the 236B:4 was as easy to achieve as it was in SCIII, though. After all, Soulcalibur is a purely tactical fighting game, and as such, it was never centered on difficult moves, input and execution-wise.