Perhaps, the modler could take a page from cockpit transparent/reflective effects. Each ice fragment would have an outer skin which, like cannopy glass, is transparent, but also reflective. The map for the skin would also have bits of frosted areas on it. Then, just below the surface, is the opaque part of the ice chunk. It would require the outer skin to be a separate submodel from the inner chunk.
It would take nore more than standard table moding or just making sure the filenamenames of the fragments match the current asteroids, to get them ingame. Making them spit out particles or shapnel when they break would require some recoding of the asteroids table, though I think said table could use an upgrade anyway.
