Blair, Here is what I do…its pretty much taken from chapters in Lightweight Backpacking and Camping. If you dont have it i'd suggest it.
First, the main difference in a poncho tarp and a regular tarp is you want to remove all line each morning. This is because when it starts to rain you don't want to have to deal with a bunch of lines dangling down from your poncho. The best way to do this with minimal lines is to cut 8 sections that are 3 feet long each. Tie a bowline knot in the end of all sections. Bring eight tie stakes as well.
First I stake the rear corners of the tarp directly to the ground.
Next I attach a 3 foot section to the front corners by threading one loop through the webbing in the tarp and taking the other loop of the cord and pushing it through the first loop then pull. This basically makes a slip knot that will be easy to undo in the morning. I stake the front corners down at approaching where I think they will need to be when the tarp is pitched.
Now I use the same slip knot technique to make two 6 foot sections… one for the front peak and one for the back peak.
The easiest way to attach cords to your poles is the place the front pole upside down (handle in the dirt) and set the web loop of the poncho through the tip of the pole. Then take one 6 foot lines (2x 3ft) and drop the loop over the tip in the pole and stake out the other end. The rear end of the tarp gets the other 6 foot section of cord (2x 3 sections) and can use a branch to hold it up or your other pole. If the pole is not adjustable you can use a piece of duct tape wound around the point where you want the string to set…lets say at 3 feet. Then attach your line to the rear peak loop with the slip know approach and wind your line around your pole just above the duct tape and stake the line down.
The last thing I do is use the final 2 pieces of cord to stake down the sides of the tarp.
Here is a picture of what it looks like…

the pitch is a bit slack as this was after a night with same decent winds.
Here is a picture using the same setup with a tighter pitch, but it is a regular flat tarp (5 x 8).

In the morning it takes about 2 minutes to take down the tarp and remove all the lines.
I realize this is a bit difficult to understand with just words so if you want some pictures showing how to thread the cords through just ask and I will snap some.
Jamie