SteveJax:

Basically, I create additional mesh elements (with ambient materials applied for the glow effect), then hide them within the figure. A morph target will bring the glow-bits into view.

For Redfern's F.L.O. robot, I placed the glow-bit within her head, just behind a transparent grille. The OpenLips morph moves it forward, out of its hiding place.

For Pilbeam's Dalek, the glow-bits are scaled-down beneath the earpieces.

Dalek animation -- Mimic test (391KB MPEG-1 video)

(Please excuse the colours ... I've only worked on the grouping, rigging, and morphs, and haven't done anything with the materials yet.)