There's no way of subscribing to your ward calendar that I know of.
The only method is to have an account and download it. As to storing the calendar on another site, I don't know what the policy is in regards to that one. My opinion is that the members would be better served if they just used the calendar as it is since there's other features available and just not the calendar. Keeping it updated would be a continued challenge.
For those who may need instructions on how to obtain access to their ward's web site note the following;
To start out go to http://www.lds.org
and click on "About The Church", then click on "Stake and Ward Web Sites". You will be given a logon screen. On the screen you'll see a link title "Obtain an Account". Click on that link.
You will need your membership number, which you can get from your recommend or contact your membership clerk. You'll also need your date of confirmation.
Once you create your account and logon then you'll be at your home ward's page on lds.org which will include the calendar as well as access to your ward's membership directory. Your account also gives you access to the other wards in the stake as well as the stake calendar.