I concur with Louis and Dave -- unfortunately, the suggestion to attempt to purge the boiler via the water wand won't work, and you'll wind up with a frozen machine -- most likely destroying the heat exchanger which would remain filled and other non-drained water components in both the boiler and HX water paths.
There are no shortcuts to prepping a machine for shipping in cold weather. In warm weather, what was suggested might save a bit on weight by reducing (but not fully removing) the water in the boiler, but, due to leakage potential, the package could get water damaged and fall apart -- you can't trust a "This side up" sign on a package to be followed by shippers....
You could not count on shipping insurance paying either -- they would say you improperly packaged the machine because water could damage the packaging and would deny the claim.
The best bet is to open up fittings, fully drain the HX and the boiler, open up the various lines that might have water in them and gently blow them out with compressed air. As Dave mentions, if there is a chamber in the group head(s) for a Glicer, that must be drained as well (E61 groups and Elektras have them, and others with similar designs).
On non-hx boilers, unless they have a drain port on the bottom, probably the best way to to drain them is to remove a top fitting and turn the machine upside down to drain all the water out, then open lines and blow the water out of them and any valves in the water path....
A final word of caution -- after having drained the machine -- the recipient of the package would need to follow whatever instructions the manufacturer gives for doing the initial filling of the boiler without the heating element from coming on. Failure to do that would likely cause the heating element to overheat and get damaged before it gets submerged by the water....
I hope this helps,
Philip



