LOTR AC3 - Any Idea?

[fiv5]

Hi , i know there is already a thread about putting the LOTR SVCD onto a dvd-r by altering header etc. , but what i want to do is quite different. I have the DIVX release with the AC3 Audio track, and also the svcd, what I would like to do is:

Demux the divx (never done this, what tools would be ideal?)
demux the svcd

resize the svcd video to 720x480
(im assuming only way to do this is {dvd2avi>avisynth with resize filter set to 720,480>then re-encode in CCE}
then remux the AC3 soundtrack with the resized SVCD video (with BBMPEG, does the DVD mux work properly?)

Can anyone recommend Authoring software that will accept a BBMPEG DVD Muxed file ?

Does this look like it would/should/could work ?

Any help greatly appreciated :)

thanks