Private message mute:
1) create pmute.lua
2) make the lua create a field under global_players_table[victim][pmute] = 1
3) in console/m.lua add a check for this field, like this:
if global_players_table[slot][pmute] then return 1 end -- abort exection

now you have a !pmute command that will mute/disable client's private messages.

to create an punmute command:
1) create punmute.lua
2) make the lua delete the field: global_players_table[victim][pmute] = nil

thats it.
dont forget to add chat-prints (<player> private messages has been muted) and checks for the field when trying to delete it
if global_players_table[victim][pmute] ~= nil then global_players_table[victim][pmute] == nil end
otherwise trying to use !punmute on a not-muted player will raise error.