The following is the quick and dirty template example of what I do when creating vmware nodes in xcat. If you are not using pxe nor vmware just exclude that line ( but it wont break anything if you keep it )

mk_xcat_esx_node.sh

#!/bin/sh
# define vaiables
#  In my real set up this is a lot more complex but if you are new to xcat
#  this should be useful enought to get started

HOST_NAME=nodename
mac=00:50:56:b0:d0:00
ip=192.168.13.16
XCAT=192.168.13.100
OS=centos6
VMHOST=vmware-of01-05
PROFILE=compute

# create the first node entry 
nodeadd  ${HOST_NAME} groups=all,$OS,$VMHOST

#  Update IP and MAC for host
chdef ${HOST_NAME} ip=$ip mac=$mac

#  Add xcat server ( in this case xcat does everything, but in bigger networks ...)
chdef ${HOST_NAME}  tftpserver=${XCAT} servicenode=${XCAT} nfsserver=${XCAT}   xcatmaster=${XCAT}

#  Add config for vSphere specific schtuff
chdef ${HOST_NAME} vmhost=${VMHOST} power=esx  netboot=pxe  mgt=esx getmac=esx

# what kind of node is this supposed to be?
chdef ${HOST_NAME}  arch=x86_64  os=${OS}  profile=$PROFILE

makehosts  ${HOST_NAME}
makedhcp   ${HOST_NAME}