$ sudo heimdall flash --recovery recovery-clockwork-5.8.4.3-skyrocket.img 
Heimdall v1.3.2, Copyright (c) 2010-2012, Benjamin Dobell, Glass Echidna
http://www.glassechidna.com.au

This software is provided free of charge. Copying and redistribution is
encouraged.

If you appreciate this software and you would like to support future
development please consider donating:
http://www.glassechidna.com.au/donate/

Initialising connection...
Detecting device...
Claiming interface...
Attempt failed. Detaching driver...
Claiming interface again...
Setting up interface...

Checking if protocol is initialised...
Protocol is not initialised.
Initialising protocol...
ERROR: Failed to initialise protocol!
Re-attaching kernel driver..
$