What do you mean by XE Certification?
Have you been certified in any other release, if yes, there should not be any need to recertify, being that not much has changed when it comes to Functionality.
Is there a specific Certification program for XE?
I did take B7333 certification and passed 3 of them (Finance module).
Visit the "KG" to find some sample of the questions asked. You have to have worked with this system for some time and be very familiar with it for you to pass it. Good knowledge of file(table) system and the info kept in them. (Finance mostly- my certifications)
It used to be open Book, and still was difficult to pass, but you may be able to pass on the GO.
Good luck.
OWman
XE, Oracle, SP16, Sun