I tried making modifications in the hal policy file, but didn't have any luck there.
What I finally did was modify ivman's mounting commands in /etc/ivman/IvmConfigBase.xml
I changed the mount command to:
<ivm:Option name="mountcommand" value="pmount '$hal.block.device$' /media/'$hal.volume.label$'" />
and that works. I also had to add the following lines:
<!-- Add label if no label exists -->
<match key="volume.label" string="">
<merge key="volume.label" type="string">usbdisk</merge>
to my hal policy file (/usr/share/hal/fdi/policy/10osvendor/20-storage-methods.fdi) under the vfat mounting section. This was because I had a few disks that didn't have any labels.
btw I am running this under Ubuntu Server 7.10