Cassidius:

You can't create new scenes (i.e. new animations), but as mentioned above there are sites such as Housemods and DCMF where you can obtain modded scene files.

Steven Dyson at DCMF is currently working with the animation files and using blender to import new animations into TM.  Who knows, if he is successful, we might even be able to create our own scenes but that is a ways off still.

The scenes at Dr. House's site, HouseMods, are the unused scenes and animations that are in the game but not used;

The Fire Extension which allows you to use all fire scenes on Tarison's 6er.

The ITC scenes which had to be used in the International Team Challenge.

The Lab Scenes of the lab set which was never released by Lionhead.

The Lot Scenes which allow you to use most of the lot animations in your movies + the Invisible Blue Props mod which removes some blue props from the scenes.

The New Scenes Pack 1 and the New Scenes Pack 2 with new scenes.

The Suicide Scenes with some suicide scenes.

The Train Scenes from the never released train set.

The Var8 Scene with some new animations.

3 New Scenes with various new animations.

The Camp-car Scenes with 10 new animations.

The Costume Scenes with 8 new scenes (48 new animations).

The Various Scenes A-D Pack with 9 new scenes/54 new animations.

!!! NEW !!! The Director-Scenes with 24 new animations.

A complete list of all scenes in the various Scene Packs:

ITC-Scenes
ghost

Lab Scenes
lab1
lab2
lab3
lab4
lab5

Lot Scenes
bar
canteen1
canteen2
cinema_exit
fight
fountain
gym
karate
lovers
preprod1
preprod2
rehearsal_com-rom
rehearsal_hor-act
rehearsal_sci
ring_of_fire
script
talk_2char
talk_2char2
talk1
tech
var_out
var1
var2
var3
var4
var5
var6
var7

New Scenes Pack 1
alienrock
billboard
car
flowerbed_weed
palm_lamp
pinball
pirouette
play_pinball
plynth
plynth_fold_arms
sarcophagus
suicide
tree
tree_read
waltz

New Scenes Pack 2

Suicide Scenes
suicide1
suicide2
suicide3

Train Scenes
train1
train2
train3

Var8-Scene
var8

3 New Scenes
bbb_bub
photographer
scriptwriter

Camp-Car Scenes
camp
cargetw

Costume Scenes
cos_alienbunny
cos_cheerunder
cos_chickenaerobic
cos_grunthapsad
cos_militgorilla
cos_priestvar
cos_weshands
cos_wolfvintage

Various Scenes A-D
change
change_auto
clapper
coach
death
despair
diner
diner2
ladder

Director Scenes
director1
director2
director3
director4

They are great when used in conjunction with Tarison's Bluescreen sets.