Finally done.
Tested in FS9 and IL-2 work fine, in FS both throttle practically have the same response, in IL-2 put second lever as prop pitch.
View of internal wiring:

The small PCB in upper left corner is only for plug wires, no active components.

This PCB have in left side plugs for 4 axis, in middle replicated Rows pins of BU0836 and in right Columns pins.
Put Bu0836 inside F-15
joystick and use two multi-wires cables between joy and throttle, one for axis, another for buttons. Only found cable with 12 internal wires - so i need use two.
Holes for buttons and LEDs intend for original Suncom programing are covered whit some plastic sheets.

I have two axis and 20 buttons in SFS - and two axis and 7 buttons left in BU0836, maybe put some extra toggle switch and pot with knob in front of SFS box...
Basic sketch of wires, SFS already have diodes in every button/HAT, so I reuse these diodes for BU0836 matrix, this simplified wiring - only the small PCB under gray thumb button require some modification.

If use one BU0836 exclusive for SFS is easy to make this MOD.
The use of HALL sensor is due lack of potentiometers options in local market. I found only cheap ones or very expensive (~25/30U$) Alps, bourns in Farnel, and no appropriated dimensions. The pot in SFS (120k) are very big.
The HALL plus magnets cost around 3U$ each.
Related:
http://simhq.com/forum/ubbthreads.php/topics/2706511/Suncom_F15_BU0836_HALL_Sensor.html#Post2706511Sokol1