Watch the Change It Up online guitar lesson by Brad Carlton from Chord Studies: Jazz Turnarounds Vol. 2
Here we have a I-vi-ii-V, but with the b5 sub applied to the vi and the V chords. Start with the Fmaj7 and notice that the C note, our soprano tone here, is going to remain as our top voice throughout the progression. Then you go to an Ab9 chord, which is the b5 sub of D7#5. From the Gm7/11 chord you lower the third and fourth voices and get Gb7b5, which is the b5 sub of C7.