Check these OIDs out.
.1.3.6.1.2.1.43.11.1.1.9.1.1 = INTEGER: -3 (Black)
.1.3.6.1.2.1.43.11.1.1.9.1.2 = INTEGER: -3 (Yellow )
.1.3.6.1.2.1.43.11.1.1.9.1.3 = INTEGER: -3 (Cyan)
.1.3.6.1.2.1.43.11.1.1.9.1.4 = INTEGER: -3 (Magenta)
.1.3.6.1.2.1.43.11.1.1.9.1.5 = INTEGER: -3 (Absorber)
If I am correct values are: -1 / -2 / -3 / -4 where -1 is full ink. You need to double check that 