I did not say an "investment" doesn't include an investment in labor, of certainly does.

The context was "bootstrap without investment." The answer is, you don't, you either invest yourself (capital or labor) or you look for investors. You don't "make someone a co-founder," that strongly implies that they are a passive actor, you look for someone willing in invest, you look for someone looking to start a company. You don't have "employment agreements," you have "business partnership."