"Live" CD Mounting file systems

[irdgtom.thompson at edd.revealed.net]

Hello all,
 I am trying to build a FreeBSD 5.1-RELEASE-i386 based "live" cd and I am having
trouble getting the filesystems mounted.  The kernel boots but then tells me
that it cannot find the root file system.  From what I have read it appears
that I need to make a memory filesystem to load part of file system on. 
 
Does anyone have samples on how to actually accomplish this?
 
Thanks
Tom