[Custom Achievement] Functions for counting kills

[SCP-5666-Akira.exe]

Greetings,
I'm asking here because I didn't found a solution for this:
Since Beardlib got the Custom Achievement API, I wanted to do Weapons kills but the problem is I don't know what hooks, function and source hooks I have to use to count the kills.
If anyone have a tutoriel, a guide or know how to do, i'll be very grateful.

[SCP-5666-Akira.exe]

Uping the subject since I made my own research and tried something.

I found the Lua for those achievement.
"statisticsmanager.lua"

And I think, I need to use these functions:
"StatisticsManager:killed", "StatisticsManager:_add_to_killed_by_weapon" and "StatisticsManager:_get_name_id_and_throwable_id"

In this case, I don't know where to place them in the "statisticsmanager.lua" in my custom achievements' hook.
Can someone help for this ?
Thank you.