1. su - root
2. Upgrade WAS/IHS and Plugin fix pack level to 7.0.0.27
Refer "Recommended fixes and settings for WebSphere Commerce Version 7" for further details
http://pic.dhe.ibm.com/infocenter/wchelp/v7r0m0/topic/com.ibm.commerce.install.doc/refs/rigrecfix.htm

Download WAS 7.0.0.27 for your os version from here
http://www-01.ibm.com/support/docview.wss?uid=swg24033882

upgrade IHS, Plugin and WAS using filent install files
<WAS_UPDATE_INSTALLER>/update.sh -options "/home/wasuser/git/wcs_scripts/install_files/ihs.update.response.txt" -silent
<WAS_UPDATE_INSTALLER>/update.sh -options "/home/wasuser/git/wcs_scripts/install_files/plg.update.response.txt" -silent
<WAS_UPDATE_INSTALLER>/update.sh -options "/home/wasuser/git/wcs_scripts/install_files/was.update.response.txt" -silent

The install files used of this upgrade can be cloned from my git project locate here
https://github.com/hariinfo/wcs_v7

Check the output from <WC_HOME>/bin/versionInfo.sh to validate upgrade was successful

Name IBM WebSphere Application Server - ND
Version 7.0.0.27
ID ND
Build Level cf271250.01
Build Date 12/13/12
Architecture AMD (64 bit)

2. For GUI install refer this section
http://pic.dhe.ibm.com/infocenter/wchelp/v7r0m0/topic/com.ibm.commerce.install.doc/tasks/tigfepguiinstall_on7_steps.htm
Here are the steps to install on developer toolkit

3. Silent install can be used to upgrade server environment.

/WC_V7.0_-_FEP6_FOR_MP_ML/server/install -options /media/sf_linux_share/WC_V7.0_-_FEP6_FOR_MP_ML/server/responsefile.txt -silent -is:javaconsole

Check the output from <WC_HOME>/bin/versionInfo.sh to validate upgrade was successful

Installed Product
--------------------------------------------------------------------------------
Name IBM WebSphere Commerce
Version 6.0.0.0
ID wc.fep6
Build Level 130322dev
Build Date 22/03/13

3. Restart DMGR, node agents and WCS instance to validate your instance.

WCS Feature Pack 6 Upgrade