Linking Pendulum to Clock

I'd like suggestions on how this is done. I know I an link one moving part to a static structure (Clock) but a prim pendulum would probably consist of about three parts. I know I have seen cut-out ones which would be 1 part. Any help would be appreciated.

You would need to update the positions of each prim constantly. The result wouldn't be very smooth and would put unneeded load on the sim.

The better way would be to animate a texture, as you said you have already seen. Simply animate the texture to rotate back and forth.

Something along the lines of:
llSetTextureAnim(ANIM_ON | ROTATE | LOOP | PING_PONG | SMOOTH, ALL_SIDES, 0, 0, 0, 0.1, 0.1);
Will need to be adjusted to your needs.

For more info on animating a texture:
http://lslwiki.net/lslwiki/wakka.php?wakka=llSetTextureAnim

You can do a sort of pendlum in one prim, using a torus

Dimensions X: 1.00 Y: 0.01 Z: 1.00
Path Cut B: 0.750 E: 1.000
Hollow: 15.0
HoleSize X: 0.10 Y: 0.10

Leave the rest the same. Then apply a totally transparent texture to the "noodle" face of the prim. Texture the remaining faces to taste.

For Extra awesome..

Dimensions X: 1.00 Y: 0.01 Z: 1.00
Path Cut B: 0.750 E: 1.000
Hollow: 40.0
Hollow Shape: Triangle
Twist B: 90 E: 90
HoleSize X: 0.10 Y: 0.10
Profile Cut B: 0.05 E: 0.95

Add some shiny, contrasting colours, nice contoury textures, and some bumpiness. The results can be quite good.