Anyone here added a real time clock to the Pi?

It's pretty trivial in principle but "The Internet" seems to be littered with various ways to configure the Pi to use it, most of which include adding it to /etc/rc.local rather than (for example) /etc/init.d/hwclock.sh.

My objective is to have a solution that (a) requires minimal changes to a stock Raspbian (ie the fewer files to add/modify the better), (b) will detect whether an RTC has been added and roll back to using the fake hwclock concept otherwise, (c) use NTP to maintain the clock (including writing to hwclock) when an Internet connection is available and (d) do all this as early into the boot process as possible so minimal services start up with an inaccurate clock.

All of that sounds like a fairly desirable standard but most solutions I've found seem to fall short of at least part, and frequently most, of that.