Chungachanga,
I don't know about covers, but you might check out the cleat pontoons nashbar.com sells for $3.95. I have ordered some and should get them today or tomorrow. Based on the SPD road cleats I have seen, these are probably a little metal base with rubber blocks on each end. They bolt between cleat and sole on any of the SPD-type (two screw) cleats. The two "pontoons" then, I hope, allow you to walk in the shoes without the cleats touching the floor. Give me a day or two to get mine and try them so I can report back to you. For $3.95 I thought I'd give them a try for my Egg Beater cleats which look very similar to the Time cleats.
Regards,
Raymond