So, I finally bit the bullet and started to use some of the advanced functionality in Flash CS4.
I have a side-on shot of an SUV type vehicle and I want the doors to open out like cupboard doors - like the ones on the old Cadillac in the first Matrix movie..

There's no way I'm hand drawing that on singles - and I don't want to go the 'full 3d' route - though I have the skills if it came to it.
I used motion tweens and the 3d manipulator to move the doors and also animated a 'return' behind them to give the (2d) doors some thickness.
Here's a short (4mb) quicktime movie showing the test piece working.
I've now got to go back in and give it a hand-drawn look to match the rest of the cartoon.