best way to drain torque converter still in truck

[dbmx66]

trans cooler in the rad sprung a leak, coolant has been going into trans.
i drained the trans fluid (strawberry milkshake) out, but there still some in converter.

id rather not deal with unbolting the engine and trans to pull it off and drain it.

some one told me i can drill and tap a 1/8npt on the converter, drain it, then plug it up. any opinions?

and other ways to do it?

thank you