Probably you should post to port-xen instead.

  I'm trying to get xen up and running on NetBSD-i386-current. The
  boot process of xen stops after the detection of the firewire
  controller fwohci.

Is what you mean?

  xen boots
  the dom0 kernel starts to come up and stops after fwohci

What happens if you boot w/o xen?   Is fwohci found, and what's next?

You might try making a XEN0 kernel w/o fwohci, or what's next.

It might help to post the full dmesg of the machine when running w/o
xen; someone might have an observation about odd hw.

-- 
        Greg Troxel <gdt@ir.bbn.com>