The mod is not perfect as a gameplay mod, it's designed solely to show sims doing these actions.
This mod shows five animations which were created for the game from the beginning, but which are not in use. Thanks to heidi137 for looking at my file and altering a 'transition duration' setting to a slower value, and suggesting different values for this (I've chosen the value used in the mod after testing various values/numbers.) Sims now slide into the new posture in plain view, so it looks more normal. This mod is updated to V2 with a fix for the sims moving instantly to the new posture at the beginning and end of these animations.