Download
Sun Ray Server Software (SRSS) 4.2 http://wikis.sun.com/display/SRS5/Home#tab:SRS-5-Documentation Patches for SRSS4.2 http://www.sun-rays.org/srss.html#patches

Preparation:

Solaris Version: SRSS 4.2 requires Solaris 05/09 (u7) verify you have the correct version.
#cat /etc/release
Solaris 10 5/09 s10x_u7wos_08 X86
Copyright 2009 Sun Microsystems, Inc. All Rights Reserved.
Use is subject to license terms.
Assembled 30 March 2009

Installation:

1.) Got root?
su

2.) Extract the software:

# unzip srss_4.2_solaris.zip

3.) Install Java (SRSS 4.2 needs java 1.6 or higher.)C
Check your java version with the following command:

# java -version

Install java 1.6 on your system. The script is chip dependent. Pick x64 or Sparc

# ./srss_4.2/Supplemental/Java_Runtime_Environment/Solaris/jre-6u13-solaris-i586.sh  
# mv jre1.6.0_13/ /usr/jdk/  
# rm /usr/java  
# ln -s /usr/jdk/jre1.6.0_13/ /usr/java

4.) Install Apache Tomcat

# /usr/sfw/bin/gtar -xvz -C /opt -f srss_4.2/Supplemental/Apache_Tomcat/apache-tomcat-5.5.20.tar.gz  
# ln -s /opt/apache-tomcat-5.5.20 /opt/apache-tomcat

5.) Install the Sun Ray Server Software

# ./srss_4.2/utinstall  

take all of the defaults
Note: Now is when we would apply patches. Since this a new release there are not any yet.

# reboot

6.) Configure the Sun Ray Server Software:

# /opt/SUNWut/sbin/utconfig  
Take all of the defaults except for:  
Enable remote server administration? (y/[n])? y  
Configure Sun Ray Kiosk Mode? (y/[n])? y  
#reboot

7.) Configure the parms file and tell the server what firmware to offer out

# mkdir /tftpboot  
# vi /tftpboot/srssconfig  

The file should look like the following:

servers=  
# /opt/SUNWut/sbin/utfwadm -A -a -V -i /tftpboot/srssconfig -f /opt/SUNWut/lib/firmware_gui

8.) Turn on LAN connections:

# /opt/SUNWut/sbin/utadm -L on  
# /opt/SUNWut/sbin/utrestart -c

At this point you have a basic Sun Ray server up and running. Any Sun Rays on the network should be displaying the Solaris log in and you should be able to log into your Solaris server through a Sun Ray.

Personal Notes:
I did use a second NIC for the SunRay, so I did configure an pcn1 with 192.168.128.1 on static on Solaris 10 installation.
Therefore I need to reconfigure SSRSS4.2 to use that:

# /opt/SUNWut/sbin/utadm -l # show SRSS config  
LAN connections: On  
Sun Ray interconnect framework is not configured  
# /opt/SUNWut/sbin/utadm -r # remove SRSS Network Config  
Sun Ray interconnect framework is not configured  
# /opt/SUNWut/sbin/utadm -a pcn1 # configure SRSS for pcn 1  
#got an error here as it was already configured during Solaris 10 installation - so lets remove that:  
# mv /etc/hostname.pcn1 /etc/hostname.pcn1.bak  
# /opt/SUNWut/sbin/utadm -a pcn1 # try again and it works!

Taken from: http://blogs.sun.com/acworkma/entry/how_to_build_a_sun2