My primary drive is an SSD and I am trying to avoid the writes to it every 20 min for the purpose of the autosave function. Is it possible to change the default location of the quicksave files?
Look in Preferences; You can set time between saves and number of files to save. Most people are cranking up the time between saves to the max to avoid conflict while trying to work, it might not be convenient for you when it chooses to save. 
I actually do not mind the auto save function in and of itself. Zbrush has the ability to crash and inopportune times and that feature has been nice for recovery. My main issue is, after recently updating to a SSD HD, i do not want the frequent writes (quicksaves) to my primary hard drive. I would like to change the destination to my secondary drive.
Not as far as I can tell by any menu option.
Something search turned up>> http://www.zbrushcentral.com/showthread.php?182724-lost-hrs-of-work-because-of-quick-save-(beware-of-quick-save)&highlight=Quick+save
And http://www.zbrushcentral.com/showthread.php?177928-Quick-Save-hassles-Answered&p=1020102&viewfull=1#post1020102
Read page 4 of the “ZBrush4_R6_whats_new.pdf” in your Documentation folder of the ZBrush 4R6 directory.