My experience :
First : same problem : my tablet don't want to connect with my HD2 (Rom WM NRGZ), while my laptop can do.
But today I show my Iconia 500 to my work, and a friend with her HTC Desire HD with Android custom ROM and wifi tethering connect it without problem...
But it's not a USB modem it's wifi tethering (I'm probably off topic ?)
HTC ONE 32 Go Silver
Rom : SD v 14.3 ULTIMATE
Radio : 4A.20.3263.16_10.38k.1157.04L
Hboot : 1.55.0000 from Base 3.62 Modified
Firmware : 3.62.401.1 (10.11.2013)
Android Version: 4.3
HTC Sense Version: 5.5