I have been reading the wonderful guide to softmodding the 3.1-4.1 Wiis by Dogeggs, and I was wondering if there has been a work-around that would allow my Wii to play DVDR.
There is no software-based solution for the hardware programming in the D3-2 chip. After you softmod your Wii, you can play backup games on an external USB HDD.
emclinux is correct, you can play either a compressed or noncompressed game ISO backup from the SDHC. A typical Wii game ISO is 4.37 GB. You can also elect to format an SDHC card in the WBFS format and use a USB loader to play from the SDHC card.
Most of the loader applications offer a menu from which to select your load source: disc, SD, USB.