Customizing lisp-mode

[Jérôme Haguet]

Hello

I would like to customize lisp-mode because we use it to edit files for 
a Lisp-based dialect

Here are two examples of what I want to do :

1/
In (dce blabla ...)
a/ should be colorized like (defun bla_bla_bla ...)
b/ should appear in index menu

2/
In (my_lisp_prefix.my_lisp_symbol bla_bla_bla ..)
my_lisp_prefix should be colorized with font-lock-type-face.

What is the best way to do it ? Customize lisp-mode ? Create a new mode 
      ?
What variable should be modified ?
I try to play with lisp-imenu-generic-expression to achieve 1-b without 
any success.

Thank you for any tip