Unless the eMac doesn't have a Superdrive, in which case the options are to save as a disc image with iDVD 5 and burn with Toast, or to forget iDVD and use Toast's plug & burn feature to import and burn the DVD. Toast's plug & burn won't edit, either, except for trimming at the start and end of the title.
20" G5 iMac iSight, 14" G4 iBook, Mac OS X (10.4.3)