No, the trunk port must be OOS to change the wavelength. And if you have the circuits provisioned as OCHCC, you probably have to delete the circuits and trail since these are all logically provisioned to a given wavelength. And you'll probably need to delete and rebuild internal patchcords, which requires that no circuits/trails are provisioned to the port.
If you only have an OCHNC, you should be a little better off, but in this case, you wouldn't have provisioned circuits or internal patchcords anyway.
