How to disguise an Ogre Mage into a Formian Myrmarch?

[Oryan77]

Is there any legit way for an NPC Ogre Mage to trick Formians into thinking he is a Formian Myrmarch without adding levels or templates that will raise his CR? It needs to be something he can do periodically throughout the day and within a CR8 budget. Using scrolls of Shapechange isn't the sort of thing I have in mind.

I'm looking for something that lasts for hours rather than minutes. I'll even go with mind altering spells that trick Formians into thinking that he looks like a Formian Myrmarch.

[Malroth]

a scroll of Heightened Illusionary Script chosen to convey the suggestion "This Guy is a Formian Myrmarch" will fool between 50 and 90 percent of the formians for days at a time if cast on an easily visible article of clothing, but having at least 5% being able to tell the difference due to making their will saves would be problematic so it should only be used to supplement some other method.

[Lans]

It could try the disquise skill. -10 for different race IIRC, but I'm sure theres a way to get it high enough

[TuggyNE]

The main problem with all of this is that every time any formian attempts to communicate with the ogre mage, they'll be reminded again that this particular "myrmarch" is somehow not connected to the hivemind. Which means another save on any spells that allow disbelief, and with a bonus no less. And unfortunately, such communication is "constant" according to the formian entry.