I am reasonably new to MacBSd and I am having a problem mounting the /usr
on to a partition in the Install Utility.

I have a IIcx and was never able to get 1.1 to boot in multi-user mode.  I
wanted to see if 1.2 would work or not, so I installed it on a 100MB HD
with a single partition for /root and /usr.  This worked perfectly. (I am
very impressed with the stability of 1.2)  

Now, I am ready to create a usable system, so I have acquired a 730MB
Quantum.  I used Silverlining to create the following partitions:

# 128606 Root (SVR_2)
# 3072   Eschatology
# 553600 UNIX Slice 3
# 20480  Swap
# 10000  Macintosh

I ran Mkfs on the Root and UNIX Slice 3 partitions.  I then followed the
Install instructions and I am trying to mount the second UNIX partition as
/usr.  I built devices and go to the MIni Shell.  When I type

  mount /dev/sd0g /usr

I get:

/usr : No such file or directory

I tried creating a directory with mkdir, but then the above command gives me

/usr : Invalid argument

Any suggestions would be greatly appreciated.