Photoshop :: Stitching

I'm making skins for Vst software synthesizers & FX and use Photoshop CS2 (and partly 3ds Max 7) for my projects.

The main tricky things I face problem with are VU meters, faders and mainly knobs. In general all I have to do is make 128 (or less) differrent frames of the moving knob and then stitch them perfectly one above the other vertically and then export the final image (the mondage) as tga file 32 bit uncompressed with Alpha channel for the transparency. They must be perfectly stitched (not even a pixel wrong) or else the knob or fader will wobble as you move it.

I manage fine with square VUs & faders where no transparency is present (I have also recorded an action for this) but can't find a way to deal with frames which have transparent background such as knobs or circular VUs (or even square faders which have a transparent space around them).

The procedure I follow is:

-Open frame1 file (which also has Layer Fx as shadows, bevel etc)

-Ctrl+click on the knob layer icon to select it.

-Select inverse

-Layer Mask-Hide Selection (from the Layer menu)

-Canvas size: same width, double hight added down

-From the Channels tab I make visible the mask I created earlier

-On the image: Magic Wand (not anti-aliased checked, tolerance=32) on the unmasked square underneth my mask to select it

-Delete the mask channel.

-Open frame 2 document

-Select all & Copy Merged

-On frame 1 document: paste into.

-.....I continue in the same way for all the frames till done.

2 problems:

1) Sometimes the frames are not perfectly alligned to each other causing wobbles while used as knobs or VUs.

2) If what I design is not dead centered (sometimes I want it to be this way),

then when I Paste Into, Photoshop automatically alligns it to the selection borders (the center of the square selection) even though I have deselected Snap from the View menu. (..don't forget we are talking for transparent background)