Digital BW, The Print

I'd like to revisit the question of profiling these printers. In normal
colour mode presumably the printer just operates as an 8 channel device and
the driver does a CcMmYKlKllK separation when it receives the RGB file.  But
how would one profile the B&W mode?  Arguably one should send a test chart
to the printer, print it in this mode, read the patches and calculate a B&W
Mode profile.  But I don't see how this part can be done by conventional
profiling software.  So we can profile Colour Mode but not B&W Mode?