I think besides just allowing for a separate color palette or using another option for local colors (e.g. $rgb), it might be worthwhile to try and get the protocol standards updated to include more colors so that all clients can make use of a larger standard set of colors locally and remotely. It does mean people have to update their clients, but that really isn't such a horrible thing.
Of course, I don't know that anyone will get the right people together to make that kind of protocol/standards change on something that sees relatively little use. But who knows?
