So I've made it finally - I ordered it from one guy at polish thundercat forum..
Gear indicator comes with 9 cables - one does nothing
one is "+" and 6 gears + neutral (0). All I needed to do was modify neutral switch and connect the cables from gear indicator into actual "sensor" of gear.
Didn't took actually photo of DIY - neutral switch - but this is pretty easy. All you need to do is:
1. Take your neutral switch out and insert a plasticine or sth like that and take a mold at every gear to define where stops neutral switch on every gear.
2. drill the holes
3. hammer the nailes (for 6 or 5 gears - but without neutral since you have it already with stock neutral switch)
4. get some kind of two component adhesive (glue?) which will act like metal after harden and put it on your neutral switch to align the level of whole surface with original neutral switch pin
5. polish it to have your nails visible and have your surface smooth
6. add some glue from the other side of the nails to seal neutral switch
7. shorten the nails if they are too long
8. Solder your cables from gear indicator with your nailes
9. Get ya sh... 2gether;]
10. plug "+" to headlight or ignition and enjoy it;]
Basically if you know anything about electronics you can make your very own gear indicator - except of what I described you need to buy 1digit LED and some basic electronics + wire - I've heard that making those thing should take less than 10 minutes if you have skills
(+ time to make 'cover')
I'll try to take a photo of it in less sunny day - it is though poorly visible at sun
I'm now thinking about making electromagnetic indicator to make it visible at every condition
So one photo is poor, another is neutral switch before from inside and another one is neutral switch after but outside - mounted and soldered.