You'll never really get the fluctuent tempo to follow (automatically) your Imported Wav File.
The thing Live could do easily is to force the tempo of your file to respect a steady or fluctuing premade tempo. But if I understood right you want it the other way around.
Here's what I would do, (I don't know if that helps and I hope it will make sense/ and it does implies you hopefully have the sense of rythm
-1st Import Your track in arrangement view with warp mode Off.
-Tap tempo while playing on the First measure so you have an approximation of BPM for a starting point.(You'll hear your file jumping a little but it's just to hear the tempo of the first measure)
-In Preferences/RECORD / Put Preroll to 1 bar.
-Hit the rec button and be ready to tap tempo along the song (hear the audio behaving nicely )IF you extend the master view at the bottom you'll see you are recording the tempo automation.
-I think it's the closer way to get it done but it requires tapping trough the whole song.
-You can then slice to midi part of it and try ajusting tempo so it matches the grid section by section.
(you could also probably boost the bass and cut the rest of frequencies then slice to midi > force to a single kick sound and then use something like B-keeper ... but I don't have the link and have nerver used it yet)
If anyone else has an idea ...