I got CS5 but I'm not good in using that software. Anyone can give me a short guide on how to use it to paint the livery template?
Normally, I'd PM this, but given the interest, I'll share how I do it - your flight mileage may vary.
In Photoshop, I will take a template and select all of the white areas within the aircraft (not the windows, engines, etc. - anything you wouldn't want to get painted over) using the Magic Wand (sensitivity of 10 or 12, all boxes checked). Then, invert the selection. Next, create a new Photoshop file with the same size and a transparent background. Copy the previously selected image into the new blank file - you should now have a "hollow aircraft", with the transparency "checkerboard" for the interior, not counting windows, metal parts of engines, etc. Save it as a GIF (which allows transparency). This gives you a "see-through" plane.
You should now be able to go into Illustrator and use the original template as a guide for your work. I usually cover it up with colors, text, etc. - see my own livery or the Lineas Basque or Mythos Air liveries for examples. I will then place the transparent template I created over the work (be careful of your alignment), which will then only show the portion of the color/text/graphics/etc. that would show on the aircraft.
It takes some practice, but I managed to figure it out in an hour with no help - hopefully this will shorten your learning curve.