Is there some way to trigger adding a specific product to an open cart?

[DrByte]

for now, anyway, he doesn't have any one thing or combination of things that does this.

Judging from http://www.thatsoftwareguy.com/zenca...o_bonanza.html it seems the majority of what you've said is indeed available with his plugins. Which specific feature is missing? Perhaps it's more prudent to supplement with something that specifically handles the missing requirement than writing everything from scratch.