The above screenshots were from the anamatic. In the animated project, I have the character animation in a comp and was planning to duplicate it, make it 3D, add some scale and orientation, then use bezier warp or something to get it to stand up. However, this method did not work as the shadows weren't very successful, especially when the character sits down:
cc slant might help you... it makes a pretty good angled shadow. try this:
duplicate the character comp and add fill (to make it the shadow color) and then add cc slant.
in the slant settings, set the floor point to be at the height of one of the feet and then adjust the slant and height settings to get an angled shadow similar to how you want it.
then add linear wipe (love the cc slant effect). this will be to crop out the top of the figure. set the wipe angle to zero and drag the completion setting to about where you want the shadow to move vertically up the wall.
now duplicate that layer, delete the slant effect and set the wipe angle to 180 (to invert the cropping). position that layer to match up with the angled shadow.
i think you can get close with that method.
another method might be to make the figure comp a 3d layer, create 2 more 3d layers and position and angle them to be a floor and far wall. then use a 3d light to cast the shadow, adjusting the light to create the shadow as needed.