Chris,
   The preoiler draws it's oil from a fitting that replaces the drain plug
on my sump.  Keep in mind that my installation is on a Lycoming IO-540;  I'm
not certain of the pickup point or other plumbing on a Continental.  After
the pump, the oil goes through a check valve and then up to a T fitting in
the line going from my crankcase to my oil cooler.  When the pump's running,
it basically pressurizes the oil system without any parts moving.  I leave
it on for about a minute, shut it off and start the engine.
   On my installation, I added an extra feature to dump dirty oil that's
come in pretty handy.  I put a T fitting in the output line from the
preoiler with a shutoff valve downstream of it that's normally safety wired
open.  Then off the T, I have a short line to another shutoff valve that's
normally capped off and safety wired closed.  When it's time to change my
oil, I cut off the safety wires, reverse the shutoff valve positions
(forcing the pump output out of the T fitting and through the dump valve)
remove the cap and screw on a piece of oil hose.  I then turn on the
preoiler and use it to pump all of the dirty oil out of the sump and into a
bucket.  Once I'm done, I put everything back where it was, replace the
safety wires and put in the new oil.  To date, I've yet to spill a drop of
oil using this system.  I just wish I could say the same for replacing my
filter!
   Skip Slater