Works like this.
"ABC passing 3,000 on climb to FL120 for parachute ops @ ....., request code".
"ABC, code 0510, report 2 mins. before drop".
"ABC, 2 mins. till drop, request traffic".
"ABC, clear for drop, IFR traffic is a Dash 8 10 miles west of you tracking north, report on decent".
"ABC, clear for drop"
"ABC, jumpers away, on decent"
Seems to work quite well but is a bit of a grey area.