mpjgregoire, (edited ) I learned on Thursday that #latexmk can now invoke #xelatex directly. The command I use is
latexmk -e '$pdf_previewer = q/start evince/' -xelatex -pvc -quiet document.tex
(Some people add %O %S after evince, but those are unnecessary in my case.)
The command runs xelatex, creates a pdf, and opens it in #Evince; and it continues running so that any change in document.tex appears in Evince shortly after it is saved.
I've also created an #Emacs command to run the process.