Write 2D array row-by-row in Level 5 MAT-File Format

I want to write a 2D array row-by-row in "Level 5 MAT-File Format"

Example 2D array:

123
456
789

3 write operations, 123, append 456, append, 789.

So far, I've looked at Matio VIs in VIPM, the Matlab data plug-in and VIs posted by users in the forums.  I want to know a route that works with minimal hassle.  Can anyone confirm if row-by-row is possible?  Would I be better to save as TDMS, then convert to .mat as a post processing step?