I am using pipes / line events for updating
arbitrary parameters the following way:

Make the parameters you want to update
continuously global variables, e.g gk1,gk2...
and write a litte instrument for each of them:

instr 1
gk1  init  p4
turnoff
endin

instr 2
gk2  init  p4
turnoff
endin

Then send  "i 1 0 1 val" over the pipe...