For a wheelie ( I assume you mean tail press) take a nice progressive edge out from the wake on your heels, like you would for an ollie.
Have the rope nice and tight, as you come off edge, let go with your back hand and shift your weight to your back leg and then straighten your back leg. This will get the nose of the board up, don't slow the boat speed down for this trick. I've actually managed to completely take the board out of the water doing this, fun times ;p
For the 180's I cut out on my toeside, once I've got enough speed and line tension, come off edge, shift your wieght to your front foot, left go with your back hand and kick your back leg up and out.
Not very technical but I just kinda figured them out while goofing about. But they make a change, I'm not a good wakeboarder but I have to think of the poor suckers in the boat watching me ride going HS W2W, TS W2W (usually fail but ride away) so until I can master some cool tricks, tailpresses, powerslides, boardslides and ollie varitions and switch riding adds a few more dimensions to my riding and ensure that those watching do not die of boredom. (olle surface 3, tumbleturn and ollie BS 180 are this summers surface trick goals
A hyperlite Roam make learning this sort of trick and powerslides very very easy.