To answer a couple things - if you have a login to the Elk website, then you can download RP easily. If you don't, be sure to plan ahead and contact them to get a login - they'll want your serial number if I believe. I mention this now because too many people try to wrap things up over the weekend only to find that their elk account won't get activated until monday. RP is the programming software you're looking for.
There is a CD that comes with that device although newer versions of windows don't need it - they have the driver built in. You will want to use the USB PAss Through feature of whatever virtualization software you use to assign that device to the VM, not set it for use on the Mac - although thinking as I type, I guess you can probably pass through the serial port instead once the driver is loaded on the mac - one of the two ways will work; not sure which will be best.
Having that XEP takes the Elk to a whole new level - access from your smartphone, access from any computer in the house, etc - it's money very well spent - it unlocks all the best features of the M1. Before I had it I would tell people about my smarthome but it never quite had the same impact as showing them real-time status on my phone and letting them see how I can open my garage, set the temperature, turn on sprinklers, etc - not to mention, it's saved my bacon a few times in other ways having that remote access.