Hi Venkat,
Yes, you've understand me correctly. The ESS and MSS iViews, which shows the To-Do appraisals lists, can be enhanced by using enhancement spots. There are many ways of doing so, but their main disadvantage is that you must check them every time you upgrade the system, in order to make sure that the original class/method hasn't been changed (if it has been changed, you may need to change you enhancement as well).
If you will write to me exactly which iViews you use and their type (BSP, Web Dynpro), I can try look and tell you where you should enter your code. Or you may ask your ABAP programmer to check it.
Regards,
Liran