The vanilla game does not support other image folders, and as far as I know he never posted an upgraded Improved Random Portraits mod.
However, there are some mods that can use such images, though you will likely need to rename the folder, Aric's and Ralph's mods (pre-modded v0.5.25 downloads) both support a "bodiesnaked" folder and the Intimate Pic Extended mod(last updated for v1.0a, but should work for 1.0d) supports a "intimate" folder. https://itch.io/t/1092140/intimate-pic-extended-v1