To make your new lamp a parametric lamp - where you can control the color, intensity, on/off ...and optionally other settings that might change versus the original bits, you have to open the 3D script and edit it.
See attached part of the 3D script for a saved-as lamp object that included a down-light as you described. The original color was white, and so the values for D, E and F (RGB) are 1. To make your object color-parametric, just change that code to read:
D = D, E = E, F = F ...
that's like wiring a connection between the D/E/F parameters of your object (the RGB values) and the D/E/F parameters of the light cone object. If you double click the color swatch of your placed lamp now and pick a new color, that linkage will pass the values along.
Similarly, connect up the G (intensity) parameter so you can control the brightness:
D = D, E = E, F = F, G = G,
Etc.
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