What I discovered is that if you create an EMPTY parachute and set it to "FLYING".
Then the unit you want to have a parachute, put this in the init:
this moveindriver parachute's name
Example:
I created an empty parachute and named it para1, I set it to "FLYING".
I want Bob to be in para1, so I put this in his init:
this moveindriver para1
or
Bob moveindriver para1
You can also control the starting height of the parachute aswell, with the following in its init field:
this setpos [(GetPos this select 0),(GetPos this select 1),height]
height being anynumber you want.