if you have an older PPC Mac running 10.4.11 you could download Q
http://www.macupdate.com/app/mac/20830/q-emulator
It's an emulator for Intel/Windows - it takes for ever to setup but at least you could have a local copy on your system.
Also you might want to look into Wine.
http://www.winehq.org/
neither are perfect solutions.
I agree with BWinmill on the life span issue, although I am using a Mac Pro from 2006 and have no issue's with software, upgrades, etc. So I am getting my 5+ years from it.
But I think its a bit much to ask a company to support hardware and operating systems from before the companies conception date. PPC was phased out well before Kobo opened its doors in 2009.