[XeTeX] Alternative location for output PDF files (and, ideally, all non-source files)

[Philip Taylor]

To ensure that I can continue to work on an important project in the 
event of computer failure, I have the source directory for this 
projected rooted in my Dropbox directory.  Whilst this works well in 
both backing up the sources to the cloud and (in the background) 
downloading them to another computer, a great deal of resources are 
wasted up backing up the resultant PDF file (50Mb) and a large number 
(almost 250) of small adjunct files (.aux, .idx, .ind, .toc, .log, .etc) 
at very frequent intervals (every time I re-compile the sources, which 
is typically every few minutes).  Is there some way of instructing 
TeXworks and/or XeTeX (whence copies to two lists) to keep all of these 
files in an alternative directory that is not itself rooted in the 
master source directory ?

Philip Taylor