I figured this out.
If the clock APK failed for you before, try now, folks. I've updated the file, and it should now work properly on stock devices and won't trip the malware detector.
The previous file is also safe (which I verified by decompiling it and comparing to the stock one signed by Google), but it's signed by a public shared key which is used to sign many custom ROMs and should therefore install on something like CyanogenMod without issues (whereas Google's own file won't).
Both are now linked in the post.