Need to use X as a user on a box after Sudo? Try this. Both files need putting somewhere in the path, and need chmod 755 owned by root.

x_sudo.sh

#! /bin/bash

if [ -n "$DISPLAY" ]; then
  CURRENTDISPLAY="`echo $DISPLAY | cut -d ':' -f 2 | cut -d '.' -f 1 | sed -e s/^/:/`"
  DPYNAME="`xauth list | grep "$CURRENTDISPLAY" | cut -d ' ' -f 1`"
  PROTONAME="`xauth list | grep "$CURRENTDISPLAY" | cut -d ' ' -f 3`"
  HEXKEY="`xauth list | grep "$CURRENTDISPLAY" | cut -d ' ' -f 5`"
fi
if [ -z "$1" ] && [ `id -u root` == '0' ]; then
  SU_TO="root"
  C1="$1"
  C2="$2"
  C3="$3"
  C4="$4"
elif [ -z "$1" ]; then
  echo "Unable to determine the root user. Please specify"
else
  SU_TO="$1"
  C1="$2"
  C2="$3"
  C3="$4"
  C4="$5"
fi
if [ -z "$2" ]; then
  sudo -u "$SU_TO" -i
elif [ -z "$DISPLAY" ]; then
  sudo -u "$SU_TO" -i --  "$C1" "$C2" "$C3" "$C4"
else
  sudo -u "$SU_TO" -i -- xauth_exec.sh "$DPYNAME" "$PROTONAME" "$HEXKEY" "$C1" "$C2" "$C3" "$C4"
fi

xauth_exec.sh

#! /bin/bash

xauth add $1 $2 $3
"$4" "$5" "$6" "$7"