I use solder--and I like retuning, so it's actually fun. It's an easier retune if you start with a solo tuned harp. For Hotel California in Bm (the record key) I would start with a B harmonica. The retune puts the harmonica into D6 blow (or Bm!), E6 draw.
It was Scottish harper Little Al Price who first suggested the tuning to me—He called it Magic Bop Band, so that’s what I called it, until Brendan Power politely suggested that he had first claim to the name, and he called it Power Chromatic. So that’s what it’s called, but there is no button. I will also refer to this as “Four six five six”, as those are the two chords—IV6 blow, V6 draw. Every draw note can be bent a half step, since every draw note is a whole step above the blow note. So in this key (Bb6/C6), you have Bb D F G blow and C E G A draw. One flat, so it’s in the F major scale. Draw bends are B Eb F# and Ab, so the only missing note is C#. That’s a pretty important note in jazz—so it’s useful to valve the D blow and set up the Bb to overblow. This is also the tuning I use for Tequila, and a few other melodies that need more of the chromatic scale, especially like Hotel California—the chorus starts with a bent note, that’s a little tricky, but not as iffy as overblows (for me). I also have a video where I recommend doing the Runaway solo with a harp in this tuning.