Your description of the oil change kit confuses me. Does it look like it has been used or is it something the P.O. bought but did not install? 3/4 inch barbed fitting sounds like it would replace the oil drain plug. Do you know what a "banjo" fitting is ? This is the most common type of drain plug replacement.
It sounds like your fitting will be permanently installed, a task you can not accomplish while there is oil in the engine. You will have to drain it out either through the dipstick or figure out a way to catch the oil when the drain plug is removed.
The drain plug is on the starboard side near the rear of the engine. Unless your piston rings are showing some wear there will be no pressure inside the oil pan. You do not need to valve the drain hose off but it is probably a good idea to plug it with a bolt of other plug, also keep it away from any moving parts or engine parts hot enough to melt the hose.
However you choose to drain the engine, it is best to run it for a few minutes to warm the oil and allow it to flow better. If you choose to somehow catch the oil after removing the drain plug, remember, there is a lot of oil! Like around 5 gallons. I suppose you could remove the drain plug and working quickly install the barbed fitting before too much oil drains into the bilge or whatever pan you have fashioned under the engine. Lots of things could go wrong with this approach though, it could really get messy. Personally I would rather work with an engine which had been drained, even a partial drain through the dipstick could make the job less messy.
Good Luck,
pete