is it possible to ping the inside interface of the pix firewall from dmz or outside.. if yes, what are the configurations to be done on it..
No, you can only ping from directly connected interface, ie: from outside, you can only ping the outside interface, from dmz, you can only ping the dmz interface, etc etc.
If you are connecting via VPN on the outside interface, you can configure "management-access inside" to be able to ping the inside interface.
However you can only configure 1 management-access line, not multiple lines. Therefore you would need to choose which interface you would like to ping when you VPN in.
Here is the command for your reference:
Hope that helps.