Same answers as a couple weeks ago. You have to associate yourself with a club which runs a Division I side, and then excel at that level. The Eagles draw their players from that source, along with the universities that have strong varsity rugby programs.
Word gets around about good players. Scouts come and watch good players. You wouldn't even know about it if a scout's watched you and thought "not good enough". If you've heard nothing you're not as good as you think you are.