The easiest way I've found to take an olive Oil Enema is using a rectal bulb syringe. If you are giving it to yourself, then attaching a 18 inch colon tube with a Fr diameter #30 to #32 to the end of the hard rectal tip makes it even easier.
Warm the olive oil to about 102 degrees F (39 C) before filling the bulb to make it more comfortable and easier to squeeze the bulb. You can also buy a Higginson attachment for your bucket as in the following picture:
However, for an olive Oil Enema I would recommend a #30 or #32 diameter minimum rectal/colon tube rather than the douche nozzle pictured here. You only have to insert it about 6 inches though to get good results.