Hi,
From what i have read it appears that you want to drive a two leaded bicolor red/green LED with two uC port pins. The problem is that with the selection of any single resistor the red LED draws more current than the green LED.
The simplest solution is probably to use two resistors and three uC port pins. You can then direct current as needed and also switch resistor values.
Another idea might be to use two resistors and two diodes, directing the diodes to conduct through the appropriate resistors for each color LED.
Another idea is to scrap the current two lead LED and use a three lead LED. You can then use the right size resistors for each LED and still only two port pins. I did this with a project with a tri color LED and it works perfectly. These LEDs are not expensive these days either.
A really cheap idea is to use two different LEDs one green and one red which can be wired up each with their own resistor.