If you're trying to allow any low-end user to change the time using an executable runnable to only root, you have several options:
Option 1: In the installation/setup procedures, "chmod" the hwclock executable so it can be executed by all (eg. "chmod a+x /path/to/hwclock").
Option 2: Utilize "sudo".
Option 3: Force the user to provide the root password if they wish to apply any changes they've made.
There's more than likely a reason why the executable has default permissions of being root-only, and it's more than likely best not to tamper with it; if you need to be root to run it, there's a reason for it. This is UNIX/Linux, not Windows.