Considering that the idgham of noon and tanween in waaw an yaa2 most certainly is naaqis, how do we implement this?

Question
As salamu alaykum wa ra7matullah wabarakatuh

Firstly may Allah reward and accept your efforts. We are truly grateful to have such knowledgable scholars available for us. I am truly grateful to Allah for allowing us to benefit from such blessed beacons of knowledge, and I can;t thank you enough for taking time out of your busy schedules to help those of us who are aspire to be from ahlul quran.

My question is regarding Idgham Naaqis (noon and tanween in the waaw and yaa2). It is discussed here http://www.abouttajweed.com/kb/entry/345/

Considering that the idgham of noon and tanween in waaw an yaa2 most certainly is naaqis, how do we implement this? I understand that the reason it is naaqis is because the noon/tanween retains a ghunnah, but how is this implemented?

1: Is the tongue placed close or on the articulation point of the noon?

OR

2: Does the reciter keep the tongue in the middle of the mouth and just ensure a flow of air through through the nose? (and therefore by doing this the reciter is implementing ghunnah...?)

What is the exact role of the tongue in idgham bi-ghunna of noon/tanween in the waaw and yaa2?

Jazakamullahu khairan- may Allah accept from you and grant you the highest rank possible, as you have been chosen for a great task. Please make dua for me and all other students of knowledge that we are able to attain complete and perfect recitation.
Jazakallahu khairan
Shokran

Answer
Wa alaikum assalaam wa rahmatullahi wa barakatuh,
May Allah reward you greatly for the dua' and grant you and all students of the Qur'an increased knowledge and application of the knowledge in the way that pleases Allah.

In an incomplete merging, , the articulation point of the first letter is completely merged into the second letter but not all the characteristics of the first letter have merged into the second.  In the case of the saakinah or tanween merging into the letters or , the articulation point of the or  is what is used, not the articulation point of the , but the characteristic of the ghunnah remains from the , so while pronouncing during the idhgaam the or , there is an accompanying ghunnah, or nasalization sound coming from the nasal passage. 
The tongue therefore is not near the during the idgham, but instead the tongue or lips are pronouncing only the or with the ghunnah.  

May Allah grant you the recitation of the Prophet, peace and blessings of Allah upon him, and the characteristics of the "people of the Qur'an" or ahl al-Qur'an.
Wa assalaam alaikum wa rahmatullahi wa barakatuh