hi Kaul Arun,
you can activated your own javascript and html in a formula field after you've activated Pass-Through HTML.
as Abhilash mentioned above, the Text Interpretation has a limited number of html tags that it supports. however, with pass-through activation that limit is not applicable. please note though that there is no support for the code that you write in the formula once you've done this.
please see the Users Guide at the webelements page on how to activate pass-through html. webelements is javascript and html written into crystal's Custom Functions feature.
in fact, if you're trying to create embedded controls for your report, you may find what you're looking for in the webelements function library already.
-jamie