USB host-mode on uC, to support small pre-defined set of USB devices
There are enough ways available to provide host mode with a microcontroller that trying to do it with something not intended for the role is "doing it the hard way". 

Look for devices with USB OTG" = "On the Go" capability.
These can provide either host of slave capability as required.



If  "... something like Atmel ATmega32U2 ... " includes an Atmel AT90USB64 , then yes.

ie using one of the available parts that DO have this capability is the "easy way" to go. There are enough ways available to provide host mode with a microcontroller that trying to do it with something not intended for the role is "doing it the hard way". Look for devices with USB OTG" = "On the Go" capability. These can provide either host of slave capability as required.

ICs with OTG capability of some sort

Cheapest in 1's in stock at Digikey:

AVR microcontroller with USB OTG capability $8.43/1 Digikey in stock.

PIC OTG &amp; Host capable microcontroller $4.22/1 in stock Digikey 

The PIC device is also the cheapest host / OTG microcontroller of any sort available in stock in 1's from Digikey.