How would one add a half diminished 7 of V chord in the hookpad. This is obviously a very common occuring chord.
Do you mean a half dim7 built on the 5th scale degree, or the half dim7 vii chord of the V? You can finagle both by borrowing from other modes. For example, in the key of C major, you can get a vø7 / gm7b5 by borrowing from Phrygian, and you can get the half dim7 vii chord of G by borrowing from Lydian (shows up as #ivø7 and f#m7b5).