It could be worth watching the MM NZ forum
although currently the only information appears to be that MM can
import the LINZ files but they might need conversion by a PC Program (not identified). However, my tests suggest that's not the whole story:
Perhaps I should start by saying that I usually import maps in .PNG format because the resulting .QCT files are almost exactly the same size, which suggests that the QCT format is based on PNG. PNG uses non-lossy compression (except that MM only accepts a 256 colour palette) so the files can be relatively small.
However, MM can also import .TIF files, apparently with more than 256 colours (if present), which it presumably converts during import. But compression is optional with TIFF files so they can be quite large.
So, now back to the LINZ maps. There are four different formats and they seem to all behave differently: :?
The 1:250k GeoTIFF are the most obvious to try first, but as Dales reported above MM fails with the error message. Furthermore, Windows Picture Viewer and my versions of Paintshop Pro, Picassa, GPSU, etc. also fail to read the files so it seems to be rather a "difficult" format. Has anybody any ideas what might be able to read or convert it?
MM responds to the other three file formats with an "unrecognised format" error, but that's easy to fix, just remove one of the 'f's from the TIFF extension (to make .TIF). :) Then the files are correctly imported, but of course only the 1:50k GeoTIFF is actually calibrated.
To answer my own question in the post above, only the 1:50k TIFF files seem to be compressed, having sizes of about 1MB - 20MB, compared with the fixed (per type) sizes of 140MB - 220MB of the other three formats. So it might actually be quicker to download and manually calibrate the 1:50k TIFF files than to use the GeoTIFFs.
Manual calibration seems quite straighforward because the maps carry grid lines just like OS maps. But LINZ also seem to give plenty of data for calibration so perhaps somebody will suggest a suitable method or conversion tool. Cropping off the legend and other data from the TIFF maps can be done either in a graphics/photo package before calibration, or by using Map : Boundary to Route : Send Enclosed Route, etc.
Finally, although these maps have the same nominal scales as OS (1:50k and 1: 250k) maps, they actually appear about 18% larger within MM. The OS 1:50k maps have 200 pixels/km whilst the LINZ have about 236 pixels/km (intended to be printed on paper at 300 dpi).
Well, that seems to be the situation at present, perhaps we'll be able to refine the techniques as we did for the OS StreetView Opendata. ;)