I'm pretty sure that it was me that suggested this scale in the earlier post; I was having trouble replying due the "request timed out" thing. So, here are the most common uses for this scale, and a couple of Dead specific places it can work well.
By far, the most common use for this is over the iim7b5 and V7alt chords in the turnaround of a minor blues progression. Say you are in the key of A minor, the im (home) chord is A minor, and the ivm chord will be D minor. However, the common turnaround progression consists of a iim7b5 to a V7alt (almost always a flat or sharp 9) - so in this key, you have Bm7b5 and E7b9 (or E7#9). Use A harmonic minor over these two chords, and switch back to A natural/dorian/pentatonic minor over the A minor chord. This works because the ii chord of the harmonized harmonic minor scale is a m7b5, and the V chord is a dominant - but the scale will contain the flatted ninth. This allows you to "spell out the changes" without working too hard.
Second most common place it gets used is over a static dominant seventh type chord to provide some tonal color. Works especially well if the chord has an altered tone in it (b/# 9th or 5th). Again, think of the chord as an altered V7 and use the harmonic minor built from what would be the i minor chord. For example, I like to use harmonic minor during the jam in Cassidy for a little while right before we hit the transition to G#minor. So, since this is an altered E7 chord, use A harmonic minor for this, but concentrate on the E7 and G#dim arpeggios in the scale. Sounds great, and since the #7 chord of A harmonic minor is a G#dim, it is very easy to just slip right into the transition smoothly. HOWEVER - this will work much better in some songs with extended static dominant chord jams than others, like good in The Other One, not so good in Birdsong. Try it out and see where you like it.
Third most common use is during the turnaround of a standard 12 bar JAZZ blues. It will be over the iim and V7 chords - so think harmonic minor of the root chord, like A harmonic minor over Bm7 and E7 during the turnaround. The use of the "outside" notes in this scale instead of sticking with straight A Major and E mixolydian over these two chords really makes it sound "jazz". Listen to some jazz guitarists like Wes Montgomery, Joe Pass, Pat Martino, etc, playing jazz blues tunes and you will hear it instantly once you know you're looking for it.
One more common use and another Dead related one. A very common chord progression in many tunes (including Mississippi Half Step, Michele by the Beatles, Ain't My Cross to Bear by the Allman Bros, etc) is the descending minor-minor/maj7-m7-m6 movement. In the case of Mississippi Half Step, you are required to solo over this progression (Am/Am/maj7/Am7/Am6 or D9). So how to approach this? For the A minor chord, you would play an A natural minor scale, then switch to A harmonic minor over the Am/maj7, then to A dorian over the Am7, and then to D mixolydian over the Am6 (which is also the same chord as a D9). This is because the minor/major7 chord is the im chord in a harmonic minor scale, so again, you are spelling out the changes in the chord progression by only using some very subtle shifts.
Hope this helps out. Keep in mind that this scale is best used sparingly (are you listening, Yngwie?), and can quickly sound overdone. It works well to create tension in your lines, but remember that the tension needs to resolve.
Out of the loop? I didn't know there was a loop!