This is what I was looking for, I've tested it out and it seems to work fine.
Thanks for your help.
FYI: For anyone else interested... the SQL Backup GUI must cache the email settings at some level because the only way I can get it to reflect that changes made by the stored proc call is to close out and re-enter the GUI. Even if I forced a refresh on the server it would not reflect the updated value. Thew me off for a minute when I was validating.
Also the actual values seemed to be stored in the registry here:
HKEY_LOCAL_MACHINE\\SOFTWARE\\Red Gate\\SQL Backup\\BackupSettingsGlobal\\<INSTANCE>\\