Focus blending? 1/43 scale diecasts

I'm trying to get clear infocus images of very small 1/43 scale diecast cars.I built a cheap light tent(pvc tubing) and the lighting is really good, however I'm having a bit of difficulty getting the entire car infocus.
I did do a series of images at different focus pints using a canon 100mm Macro with my 20D on a tripod, but even some of those were blurry, probably because of pressing the shutter.
The ones that were clear I tried blending using masks in PhotoShop CS3,and some worked, but others seemed to change slightly and didn't exactly line up, even though nothing moved. The changes in focus from shot to shot were only very small. I also tried to use F20 or higher, but some of the times were pretty long, well over a second or two.
Whats the best way to do a focus blend, that you have found?
I do know PS CS4 has a way to do this but for now I only have PS CS3.
Any help would be greatly appreciated.

I haven't done this myself, but I've seen some excellent results. I don't recall the name of one common app that folks have used, but Google turned up some interesting results for "photo focus stack":

http://www.google.com …=utf8&q=photo+f​ocus+stack

Helicon Focus is a fairly popular plug-in that people use for this sort of thing, but blending the layers yourself will work just as good, if not better.

What is wrong with long exposures?

Nightstalker wrote in post #9775707
What is wrong with long exposures?

On a macro level the depth of field is so slim, even at very narrow apertures, that it is impossible to get enough of an object in focus if that object has any depth.

Here, for example, is a test macro of an admittedly cheap and soiled portion of a guitar head, taken at f/22. The only way to get more in focus would be focus stacking:

I get the issue of narrow DOF issue but I didn't think that it would be a problem with 1/43 scale items. That seems very small and I'd have thought you would have got enough DOF for such a small items.

Nightstalker wrote in post #9777759
I get the issue of narrow DOF issue but I didn't think that it would be a problem with 1/43 scale items. That seems very small and I'd have thought you would have got enough DOF for such a small items.

Well, evidently the OP wasn't able to, hence the question!

The focal length is probably too long to get a reasonable DOF. You may be better off with a 60mm macro for such tasks. Or how about a 45 TS?

Focal length is pretty irrelevant when shooting Macro: Since you want the subject big in the frame, with a shorter focal length you'd move closer. DoF would be about the same because magnification is the same.

One thing that would work is using a smaller sensor camera (a compact for instance): That would give more DoF at the same magnification.

True macro perhaps, but I doubt shooting a miniature car would require coming anywhere near 1:1. So OK, keep the 100mm, take a couple of steps back, shoot again then crop the shot appropriately. Then again... 20D may not give enough pixels to crop that much...hmmmm