You will want to fill any seams and cracks to get a flat surface, and sand down any flaky paint. Use either regular or removable prepared/self adhesive wallpaper, not the kind you add water based glue to, which might not adhere well.
Just like wallpapering regular walls. Fill any seams with no shrink drywall compound. Wipe down with a damp sponge to smooth out. Then wallpaper.
Simple answer "In strips" Narrow strips on flat surface only! Had you considered painting and using a paint technique (Stencil) etc......Best wishes
I wallpapered a wall in one of our rooms that has paneling. I did exactly what William suggested. Fill the groves with nonshrining drywall compound and let it dry. From there, follow any wallpaper directions. Ours has lasted really well. Wishing you the best.
Hi Susan, this method uses a liner instead of having to fill all the cracks