Yes, you can run 2 versions but you don't want to use the Share ➙ iDVD method of older iMovie versions. You want to use the Share ➙ Media Browser method and then access the movie in iDVD via the Media Browser.
Otherwise export the slideshow out of iMovie as a QT movie file via the File ➙ Share ➙ File menu option.
Select size as 854 x 480 or 480p.
Open iDVD, select a theme and drag the exported QT movie file into the open iDVD window being careful to avoid any drop zones.
Follow this workflow to help assure the best quality video DVD:
Once you have the project as you want it save it as a disk image via the File ➙ Save as Disk Image menu option. This will separate the encoding process from the burn process.
To check the encoding mount the disk image, launch DVD Player and play it. If it plays OK with DVD Player the encoding is good.
Then burn to disk with Disk Utility or Toast at the slowest speed available (2x-4x) to assure the best burn quality. Always use top quality media: Verbatim, Maxell or Taiyo Yuden DVD-R are the most recommended in these forums.