Dan,

nothing is impossible, but:

The 16F84 doesn't have any analog ports at all.
And even if there was one, would be an Input, not an Output.

There are many ways to solve your problem.

You could use an ADC, chip, or use PWM to generate the required voltages, or an R/2R Network etc.

It all depends on what precision, resolution and speed your application requires.

You have got to give us some more details.