Is there any way I can make winrunner capture the object id of a standard object in GUI file?
Yes, for the desired object(s) add the desired attribute to the obligatory list in the GUI Map configurator. You will see the generated TSL that actually implements this. Paste the TSL code into your startup script so that it is run prior to WR coming up; this will make the new mapping available every time WR is started. Note that if you already have GUI Map files creaeted, then you will have to add the property manually or (more easily) relearn the object.