It seems to me, that steemit member who wanted to could "sign up" to be "available voters",,,, the guest form FB would click the "external vote" button and they would be taken to PayPal were they would be charged some price per vote (based on some reality of steemit voting and costs that i'm completely ignorant to) and that could be received by the private paypal account of the next "signed up" steemit member. If the outsider wanted to give more up votes they could repeat the process, this time paying to the next "signed up" steemit member in line. Obviously the signed up steemit member makes the "up vote" (maybe signed up member would have to meet a requiremnet of a minimum SP so that the vote counts,,,, or the program could match a desired "power level" that the FB person wanted with a signed up voter with the correct SP.
I don't know,,, but I think its a great idea,,, and if its PRIVATE paypal to paypal the regulators cant say or do shit,,,,, Just a thought.
I'm not an active programmer,,, and am very new to steemit,,,, wouldn't know where to begin,,, but I'm sure it could be done.