Seems the way to do this is define bus, with BusElements data type set to Boolean. By ordering the BusElements then one can even insure that the bit represents the correct bit in the word (Move Element Up/Down withiin the Bus Editor).
Though, this technique is limited to word sizes supported by Matlab. Other word (1bit > sizes < 8bits) have a bit of hole with this technique. Though, what I have done is used enumerations for these types of word sizes, and prescribed the values that conform to the size. Does leave a bit of a hole for this technique when the bitfield is outside of a natural word size that Matlab supports.