brundlefly
+1 for Set measure/Beat At Now (use Shift+M and Tab-to-Transient if prefer working from the keyboard). Melodyne will tend to set double-time tempos and make other errors that can't be corrected with the bundled Essential version, and Audiosnap has issues with placing tempo changes off the beat.
 
And Set Measure/Beat lets you set only as many points as necessary to get acceptable alignment. If the performer has tight timing without a metronome, you might only need to set every 4-8 measures in. I would start with 8, and add more if necessary. Also, you can set any point you want, regardless of whether there's a transient there or whether it's on a beat.

Yup. Much better to get right in there using your ears and musical intellect to get it RIGHT instead of relying on gimicky auto detection tools. It of course takes a little more work but totally worth it. It even saves time in many cases because instead of screwing around with faulty detection and weird convoluted auto detect settings you are just semi mindlessly performing a few simple actions multiple times and it will be ACCURATE (when done right) the first time, every time.
 
For more complex compositions with time sig changes Insert Beat/Measure combined with Insert Meter/Key change (which allows you to insert a new time signature at the Now Time... to do this go to "Project > Insert Meter/Key Change and set the new time sig in the dialog) is a really easy and reliable way to map an entire project.
 
Cheers.

Txs for your help. I have Melodyne essentials 4 installed and registered but still no way to drag any audio clip to the timeline. Any other idea? Txs!

The ability to drag a clip to the timeline was introduced earlier this year (around March, and forget which versions it applied to offhand). If you have one of those versions of SONAR installed and it does not work, be sure that Melodyne is functioning properly (simple test is to create a Region FX).
 
If you do not have a version of SONAR with the extraction capability, the method I posted above does work, but bear in mind that Essential 4 will only work nicely on melodic material, i.e., running a commercial track through Essential will likely fall on its sword with tempo.
 
Brundlefly's method mentioned above of Set Measure/Beat at Now (Shift-M) is probably the quickest method available. Depending how much variation there is on the track, you may need to use that on each beat to get an accurate tempo map (for high variations), although in many instances it can be used every measure or two (when tempo is pretty steady or recorded to a click). One caveat to that is to set the project to something close before working, since the tempo from time zero to the first inserted tempo (done with Shift-M) may get wacky otherwise - and also use Shift-M on the first beat in the song/track.

Hi Everyone,
I finally found out why the drag and drop functionality was not working for me! My annual upgrade subscription had silently come to an end in February without my knowledge! Command center was still giving me regular updates giving me the impression my subscription was still running. I just went for the lifetime update and downloaded latest version from Cakewalk download page (Command center would not get me to update to latest version...) and installed it. All now works like a charm!!
Thanks to all for your support.
Luc.