I knew that raw HID events from this keypad are reported under Linux, I need to have something equivalent for Windows.
Fortunately, there is a library for AutoHotKey called AHKHID that enables this.
You need to put AHKHID.ahk script somewhere where AutoHotKey can find it, for example in c:\Users\%USERNAME%\Documents\Autohotkey\Lib\AHKHID.ahk
By following the tutorial from the first post under this forum post link I was able to identify HID device with example1.ahk script:
vendor: 5950 product: 70 version: 17
Then, with example2.ahk script with its GUI all the remaining parts:
usage page: 65280 usage: 165
and the message format.
Every message has 9 bytes. We are interested only in the first five bytes.
00 02 00 XX - press XX key 00 03 00 F0 XX - release XX
The keymap is as follows (HEX keycodes):
02 YOURS 03 F7 / Macro1 04 F8 / Macro2 05 F9 / Macro3 07 MINE 09 BID 0A F10 / Macro4 0B F11 / Macro5 0C F12 / Macro6 0F OFFER 10 CONTACT 11 End Contact 12 Reset 13 Confirm 15 ACCEPT 16 [up] 17 [down] 18 7 19 8 1A 9 1B [tab-left] 1C [tab-right] 1D Conv Up 1E Conv Down 1F 4 20 5 21 6 22 Deal 23 Transfer 25 INTERRUPT 26 1 27 2 28 3 29 Quit 2A Cancel Inst. 2D 0 2E . (dot) 2F Back Space 2C CANCEL ALL 31 TRANSMIT
Some codes are missing. This is probably because of the fact that there are two switches under every wide key.