elisp q: what functions do I need to *visually* replace string foo with bar

[Mirko]

Hello group,

I would like to simplify the looks of my program files (programing
language is called IDL from ITT Visual Solutions).  In these I have
many variable references of the type

*self.foo

I would like emacs to display them (when in font lock mode) with just
foo, but foo being italicized.

Could someone please point me to the relevant elisp functions that can
get me going?

Thank you,

Mirko