Waheguru Ji Ka Khalsa, Waheguru Ji Ki Fateh
When a Graduate Bhai Sahib from Sikh Missionary College came to our local Gurudwara he said that you should matha tekna with ur forehead touching the ground, with your palms facing downwards, and your elbows touching the ground. He said 10 parts of the body should touch the ground. 2 feet, 2 hands, 2 elbows, 2 knees, ur forehead and nose.
However, I cannot answer the extent to which this is valid. Recall that the act of matha tekna is expression of our love and submission to Guru Ji, which is not merely a physical act, but involves humbling the mind and lowering our intellect infront of Guru Maharaj. There is huge significance of metha tekna.
The essence of Matha Tekna is that you devote yourself to Akal Purakh.
Man Tan Tera Dhan Bhi Tera
Bhulla Chukka Dee Khima
Sabh da Rakha Waheguru