Maybe this reply comes to late to be of use, but here it is:

Ska doesn't have much to do with jazz-- It's basically double-time reggae-- it came from Jamaica and got popular in the British punk scene. You're talking 2-or-3-chord tunes, simple triads (usually no sevenths, definitely no higher extensions)-- root position is a safe bet.
There are a couple of specific rhythmic parts that might come in handy, which come from reggae and are used in ska (sped up).
1: the Chuck. Play the chord percussively on beats 2 and 4. this can right around middle c or a little higher. The guitar player might play this rhythm-- its ok to double sometimes. You can play this one handed or double it in both hands.
2: The Bubble. The left hand plays the chord on all the off-beats (the "and" of each beat), somewhere in the octave or so below middle c. This part should be pretty quiet in the mix, and wants a light staccato touch.
For a good time, play the Bubble in the Left hand and the Chuck in the right hand. (remember to keep the LH quieter and to dig in more with the RH).
Solos:
If the tune is in a minor key, you'll want to use the Aeolean (natural) minor. Minor pentatonic works well, too (add the flat 5th as a grace note and you've got the blues scale). (eg in A minor, A C D E G A and Eb as a grace note).
In a major key you might try using the blues scale of the relative minor. eg, If your chord progression is C Am Dm G, you play the A blues scale: A C D (Eb) E G A. The major scale can sound pretty square, but sometimes it does the trick. It some tunes the Mixolydian mode fits the chords better.
Oh, yeah, and you'll probably want to listen to a recording of the Skatellites!
Well, theres the crash course in ska! I don't know if it does any good, but it was kind of fun to try and explain by typing in a forum!
