Timewarp would probably be the easiest way of doing what you want. But from what you say I gather it's not available in SE.

It could also be done in a round-a-bout way using a technique called Beat Slicing but doing it to a whole song could be very time consuming and I don't know if it is available in SE either.

What you are asking isn't really something simple. Your audio track most likely wasn't recorded with a set tempo so there are probably parts in the audio track where the timing is dead accurate. And it probably shifts where in some parts it's slow while in others it's fast. Trying to map a tempo to that can be very tough.

Another way of doing this would be to chop up the song into it's parts. Then in a new project set the tempo to a value that most closely matches the audio track. Now paste in the individual parts of the song and timestretch or timecompress the parts to fit in the right spots. If the variations are very small, this could work but if the timing variations are big, then this could turn out awful.

What you are suggesting does sound quite involved.

I have heard, however, that the Beat Calculator can help in this situation?

In the meantime, though, I've tinkered with the combination of the tempo track and the stretch-move. Since my audio object was pretty close to the tempo anyway, this seemed to have worked ok. Though, if my audio object was a lot different from the tempo, I suspect I would have run into some serious distortion problems, which would have required quite a bit more tinkering.

Timewarp and beat slicing techniques are not available in Cubase SE or Cubase SE3 - they are available in Cubase SL3, Cubase SX 2 and 3 and Nuendo 2/3. Still, Cubase SE is not a bad little program for the money and offers a lot of functionality.

If you do a lot of stuff with loops, midi and lots of tracks then you might want to consider upgrading to SX3 or equivalent alternative DAW.

Alternatively, programs like ACID PRo 5 or 6, Ableton Live 5 or something like Recycle by Propellerhead can do this beat matching stuff well and can be rewired into cubase.

In lieu of warp, I am pretty sure you can use Beat Calculator but I'm away from Nuendo at the moment to be sure. Give this a try:

Use the range select tool to select a section of audio, using a set number of beats (8 for example), zooming in to get it as close as you want; open Beat Calculator, input the number of beats and measures you are covering and I believe you should be able to select an option to place tempo change at object start, rather than tempo track start - that should put the correct tempo at the start of the range. You can repeat this for sections where tempo fluctuates, but remains somewhat constant over the range. It would be easier than guessing with ramps and tempo changes in the tempo track.

If you need to do this frequently in your work, then upgrading to SX might be in order (assuming it isn't in SE) - it is incredibly fast and simply to just grab the warp tool, drag it out to the right beat from the last tempo change, and shift click to place a tempo marker.