Forget transcoding, it is a lossy process that will only make your video look worse than it already does, for a video that size it will take a very long time for absolutely no benefit. DivX is not voodoo magic and will not help.
What you are looking for is a video cutter that can divide your footage into small enough chunks to fit on to DVDRs while still retaining playability. Something like
this will do the job, many alternatives can be found via Google and are generally trialware that will keep working for a week or so without payment. One thing to keep in mind is that the data capacity of a DVDR5 is 4.37GB owing to the difference in size calculations used by PCs and media manufacturers.