Here is a simple way to gradually get used to the fast Jive chassés:
1) As a preparation, I recommend replacing all the chassés (timed QUICK-a-QUICK, in your example on 3a4 and 5a6) with single steps timed SLOW. This would change the timing of your example from "QQ QaQ QaQ" to "QQ S S").
2) Once you feel comfortable with the timing, the SLOW steps can be substituted by a tap-step movement, timed QQ (a QUICK tap in place and a QUICK step to the side). Your example then becomes "QQ tap Q tap Q". Now you have the 6 QUICK counts.
3) Finally, the tap-step movement can be replaced by a QaQ. You could start by just marking the "a" in place, just to get a feel for the QaQ timing. Gradually, as you feel more comfortable, you will find the time to do an actual chassé.
Hope you find this method useful! :)
Simon