Hi Pink Trike,
B. Alan Wallace compares the Theravada meditative practice of "attending to the emblem of consciousness" to the practice in Mahamudra and Dzogchen of "maintaining the mind upon non-conceptuality", which is also aimed at focusing on the nature of consciousness. - B. Alan Wallace, The bridge of quiescence: experiencing Tibetan Buddhist meditation. Carus Publishing Company, 1998, page 257.
Unlike the other kasiṇas, viññāṇa-kasiṇa is never treated in any detail in Pali sources. In the Visuddhimagga Buddhaghosa doesn't deal with it at all, instead substituting the light-kasiṇa, which isn't mentioned in the Suttas. Given the extreme paucity of data about viññāṇa-kasiṇa, I don't see how it could be compared with Mahamudra or Dzogchen (or anything else) with much sense of certitude.
Again, Udayin, I have proclaimed to my disciples the way to develop the ten kasiṇa bases. [...] One contemplates the consciousness kasiṇa above, below, and across, undivided and immeasurable. And thereby many disciples of mine abide having reached the perfection and consummation of direct knowledge.
That's about all the Suttas have to say. Then there's an intriguing statement in the Nettipakaraṇa:
There are ten kasiṇa bases: the earth kasiṇa, water kasiṇa, fire kasiṇa, air kasiṇa, blue-black kasiṇa, yellow kasiṇa, red kasiṇa, white kasiṇa, space kasiṇa, and consciousness kasiṇa. Herein, the eight kasiṇas from the earth and water kasiṇas down to the white kasiṇa are calm (samatha). The space kasiṇa and consciousness kasiṇa are insight (vipassanā).