I think the easiest way would either be:D20 wrote:A Thousand Faces (Su)
At 13th level, a druid gains the ability to change her appearance at will, as if using the disguise self spell, but only while in her normal form. This affects the druid’s body but not her possessions. It is not an illusory effect, but a minor physical alteration of the druid’s appearance, within the limits described for the spell.
A: Let them have the disguise skill.
or
B: Allow playable races into a priests polymorph/shapechange list.
Since you guys know how I love to post D20 references, if you'd like me to post the disguise self spell, I can.
Any questions or feedback are always welcome,
Thanks,