I'll check Steve Blank out (didn't know him), but I've been trying to follow this technique ad-hoc. Like you said, easier said than done. Even friendly people aren't very responsive to requests for intros. In the few interviews I did I made a point to ask for intros at the end and although they say "sure", it's crickets afterwards.

This is a humbling realization of what salespeople are up against. We all love to hate on these guys but man... What a hustle and you need armor-like skin and insane optimism and persistence.