After downloading the IBM Support Assistance Lite for WebSphere Portal, i did extract the .zip file in wp_profile\PortalServer folder. THen go to wp_profile\PortalServer\ISALite and execute runISALite.bat to start the ISALite.
After opening ISALite you can select the problem that you want to collect trace for. I tried collecting trace for XMLAccess and decided to save the .zip file on the desktop like this
NOw click on Collect Data button. It will start collecting the trace. At this point it ask me few more questions about what is the Root directory of WAS, Portal, Login information for portal, the xmlaccess script that is failing,.. etc. At this point its started collecting trace but my machine hanged for some reason but when i rebooted my machine, i could see the xmlaccess.zip being created on my desktop that has all trace files for my server.