After deploying the Symantec Encryption Endpoint package on a client machine, there is not an option to modify or change the XPM image for a custom logo to be used on the Drive Encryption Pre-Boot authentication screen. Group policy (or Native Policy) doesn't have a provision to modify the XPM image either.
Note: The only work around available is to create a new client software MSI with the new XPM image and redeploy the client machines after uninstalling the previous client software packages. This will also require you to decrypt the drive.
Symantec Corporation is committed to product quality and satisfied customers. This Feature Request is currently being considered by Symantec Corporation to be addressed in a forthcoming version of the product.
Technical Support filed a Feature Request to add this product feature. Note that a feature request is exactly that, a request. There is no committed date for this request from the Endpoint Encryption Product Management team, nor from the Endpoint Encryption Engineering team at this time.
Please be sure to refer back to this document periodically as any changes to the status of the request will be reflected here.