Same as I did with the "Tricks of the trade" lesson on Bob Dylan's "Knocking on heaven's door", in order to practice the series of fills in this song I wrote it in powertab and then let a drum machine play the beat in the background.
I can play neither of them at speed, but at least I can play them slow now

I guess speed comes with practice. I can play "Knocking..." almost at speed and "Kansas" sounds OK but I need to gain speed.
By the way... what metronome speed would be adviseable for "Kansas City"? I have listened to a cover by Tony Sheridan and the Beatles but it is too fast for me.
I usually use David mp3's by converting them into wav files which I then trim (using a sound editing program) to the section I want to practice, which I generally slow down.
I assure you the files I wrote from David's transcriptions are fun to play and unlike David's mp3's you don't just hear what it sounds more or less: you can actually play along (sorry David).
Nothing is left to interpretation: notation here sounds EXACTLY as it should which lessens a real beginner's insecurities (at least mine). Well, it's MIDI, but rhythmwise it is as accurate as you get.
If anybody is interested, contact me and I'll send you the powertab files or mp3s or both.
Hope to have helped