Advice on booting from usb2

[Thomas Sparrevohn]

I have a 4GB SDHC card that I have formatted with ufs and installed a current kernel on - Its connected to a USB reader. 
Now here is the thing - I can boot the kernel with USB2 well enough but when it comes to mount root - it looks like
USB2 has not probed and attached the device yet and I get the "mount root from" prompt - however it does not show
the cam devices 

Any advice?