First get and unpack b2g for armhf:
Here's a ugly screendump of it running on my CRT TV. If you a HDMI display, things should work fine.
Thanks to Oleg, I used the "--screen=" option to get a much better display
LD_LIBRARY_PATH=/opt/vc/lib:/home/pi/b2g:$LD_LIBRARY_PATH ./b2g -profile profile --screen=656x545
A bit of explanation: if you don't specify --screen, b2g uses the default value "320x480".
The image is still a bit off-screen on the left side. I tried to solve that with the overscan parameters in /boot/config.txt, but that doesn't influence b2g.