Trying to understand how to lay cork underlayment mats with duck tape. based on discussions
As mentioned in the comments of my answer most quality underlayment (minus cork) now comes with one taped side.  To install the manufacturers recommend laying out the taped side in the same direction much like you will lay out the wood on your floors - for example if you have to make cuts on a row stagger them.  

Let's imagine a small room.  It is 12 feet by 12 feet.  Your underlayment is 3 feet wide and comes in a big rolls of 50 feet long.  You cut your first row at 12 feet and put it down on one side.  You would at a minimum tape the three outside edges (I know this isn't easy to tape sometimes).  Also the tape that DA01 used in his install - Gorilla duct tape -  is high quality and not spongy like "normal" duct tape.  

Now for normal underlayment I would wait until my next row was put in to tape the inside seam but for cork I will tape that to the floor too.  Basically half the tape on and half the tape on the subfloor.  So now all four sides are taped down.  

Next row.  Start with matching up the two rows and taping the pieces of cork together.  Then tape your top and bottom (2 feet each).   Then tape the side exposed to subfloor.  

Keeping going like this.  If you have cork underlayment that does not span the entire row then simple make sure that at least two sides have tape attaching it to subfloor and also taped to next pieces.  And as I said you want to stagger these like your wood if you have to cut small pieces.  Should never have seams within a foot.

Really it is hard to mess this up.  Tape everything and match up pieces.  Make sure your tape is pushed flat so your don't form ridges where your underlayment meets.  If you will have a ridge (shit happens) then simply space your underlayment out from area 1/4-1/2".

Also cork is a little different because you can lay the whole room out from the get go.  A big room is only an hour or two.  With padded underlayment you really want to only put down the area you are at because it moves/rips/tears/messes up easier.