After reading @kapone's reply this piqued my interest. If I read your request correctly, you want to convert an (E)xhaust fan to an (I)ntake one.Is there any hardware difference between front-to-back and rear-to-front airflow ICX6610s?
i.e. can I just open the fan modules and PSUs and turn the fans around?
I've got a Ports-to-PSU one here and I'd like to make it a PSU-to-Ports one. Does anyone have a PSU-to-Ports one and would mind sharing some pictures of the fan tray?
If that is the case, then you should be able to do it without the surgery @kapone mentioned. Take a look at the pictures I just snapped of my exhaust fans and you should understand why.
The tricky part would be reinstalling the plastic pins on the bottom but possible using some long tweezers. Taking them out is easy. Just be aware the locking tabs would have splayed out after being in the lock position for so long. Reinstall them from the rear towards the front and you should have enough clearance. You should also have enough slack for PSU fans because the fans are in the same orientation.
I've read on this thread Intake switches are louder than Exhaust, but unsure if that's related to the PSU or combination of PSU/fan.