Hi Otis,
I'm pretty sure that they are PC only, sadly as Grainmill is fun.
I have an old version if Win7 running on VMware that ~can~ run it, but to go there & fiddle around sucks some of the joy out.
I know I shouldn't really be saying this in the CDP forum, but other granular apps are available, especially given your very tight time constraints.
Meanwhile, there are many granular functions within the CDP system. MODIFY SAUSAGE & MODIFY BRASSAGE might suit you.
Have a look through this :
http://www.ensemble-software.net/CDPDocs/html/cgrogrns.htm