The first person support person I spoke with at HostMonster said he would need more information from you on what they need to do on their end, and as a matter of fact hadn't even personally heard of Shopsite.
I tried chatting with a second support person, who had more information. He said I would have to wait until they configured and tested Shopsite before the upgrade became available. They don't have an ETA.
Yes, I have Linux.
Jim wrote:Talk to your hosting company they should have access if your store is hosted on Linux. If it is on one of the other supported platforms it will be a couple of weeks before it will be available.