configure pc as router, possible?

Hi guys.. I wnana to make my pc as router without go through real physical router. Following is my home network structure.

Unifi modem > DLink TM router > pc client 1,2,3
So, I wanna to make it like this :

Unifi modem > (pc as router : wireless internet sharing) > pc client 1,2,3

Possible? required any software to do that?