wallpaper over gloss?

[CarlaLaLa]

i have just has a new window fitted and secondary glazing removed. i would like to paper inside the recess but wall and sill has about 10 layers of gloss on sanded with course paper with electric sander and only got one layer approx off (now only slightly un shiny) any ideas how to get this pint off quicker!! covered in dust and getting very stressed!!!