To add themes, open up dvd2.wad, find the one you want to replace, and import it. I don't think the size matters if you are using XXIExplorer 1.2. Titantrons are located in the cutscene/video folder. And the .res files are extractable in v1.2 of XXIExplorer, but I haven't had much luck importing them in. It usually causes a disc-read error message to show up. If .res files are extracted with 1.2, edited, and imported with 1.0, it seems to work fine.