You mention "carving out" episode titles, right? As I understand it, you're meshing footage from the movies with Super to create new episodes, and you want to recreate the previews to match the new titles you're giving the episodes? If that's true, all you really need is just Aegisub, the "Gamer" font that the titles are made from, and the new preview footage; just type up the new titles as subtitles onto the footage, cue them to start when you want them to appear in the preview, and then just hardsub using Virtualdub. It's what I've done for my own fansubbing and want to translate the titles in the episode previews (since having the translation on top of the Japanese is super clunky). Here's the way I go about it, but note that I work in .avi because it's easier to work with; I use Virtualdub, Aegisub, and AVIDemux V2.5. You can either encode to .avi and then back to .mp4 or whatever format you're using when done, or use AVIDemux for the selective video exporting I mention below, since it should let you do that to .mp4/etc files (but for the hardsubbing, I'd recommend working with .avi and then converting at the end).
Ideally, you should first encode the new episode preview footage in uncompressed/lossless format without sound, then encode a second compressed version to use in Aegisub (I don't know about the newer versions since I'm comfortable using V2.1.6, but that one usually crashes when you try to fiddle with a lossless video). I'd also "direct stream copy" the rest of the episode into its own video file without sound to come back to later (in AVIDemux, this would be selecting the frames, hitting "Copy" for video, and saving). Once you have your title.ass subtitle file ready (and in Aegisub, you can also tweak the border and shadow depth until it matches the look you're going for, and add a fade if you need to), load the lossless clip in Virtualdub, use the VSFilter plugin to load title.ass, check to make sure it looks the way you'd like, and then encode it to the codec format you're using for the rest of the episode.
More often than not, though, despite them using the same codec and being soundless, Virtualdub won't let you just append the subbed preview and the episode proper ("byte 14 in the index" is usually the error I get; if you don't get it when trying, awesome), so here, I'd use AVIDemux to open the rest of the episode (if prompted with a packed bitstream, don't have it unpack it) append the newly hardsubbed preview, and save the full no-sound episode. Then, I'd open the full video in Virtualdub, go to "Audio" and load the audio from the full episode you already had, go to "Video" and "Direct stream copy", and save the final full video.
Now, if you have to work in .mp4/etc, you could always use XVid4PSP to hardsub the preview and clip the rest of the episode. If you're using Sony Vegas or something, you can then drag the hardsubbed video into a project to append it to the rest of the episode that way. If you went the route of encoding the preview in .avi, you can use XVid4PSP for an HQ conversion to .mp4, or the program of your choice.
Hopefully that helps, assuming I got the right gist of your plan here; let me know if I should explain anything! If I got the wrong idea, I hope some of it helps, haha. I've been keeping tabs on this project, and I'm curious to see how it goes.