Airnav will give you the general use ATC frequencies for HIO, but not the airshow specific frequencies. During the airshow, HIO tower will hand over control of the airspace to the airshow 'air boss' who usually uses a different freq other than tower. Also, most teams have individual freq's for for,action coordination, etc.
If anyone has airshow specific freq's for 2015 it would be greatly appreciated.
iPad Air