First up, if possible, remove the center column from your tripod (you may need to also remove an end cap from the center column as well). This will make it easier to select the proper hardware and to drill the appropriate holes later. Speaking of hardware, you'll want to get a bolt and nut which is wide enough to go through the center column. An S hook which is about one inch wide and two inches long will closed and hung from the bolt on one end, so make sure it is small enough that one end (when closed shut) can fit inside of the center column.
Remove the end cap from the center column if necessary
Remove center column from tripod
Get an S hook which can fit in the center column when closed
Get a bolt which is wide enough to go through the center column