If you are still looking for a Google solution, there is one possibility, although it is pretty cumbersome too. I have been trying to do something similar.
You would need to share the calendars within Google. For example:
Main Calendar – stands along
Employee Cal 1 – shared with main
Employee Cal 2 – shared with main
(and so forth for all employee calendars)
As far as I can tell, you will have to get the owners of all of these calendars to share them for you. I don’t know of an admin tool to do it.
Then, log into the main calendar (through Google). Go into Calendar Settings > Calendars > click the main calendar and about halfway down you have the embed calendar section. Click Customize the size & other options. Then (at lower right) select all of the calendars to display (all employee calendars). Also make any other display selections you want such as colors. These selections change the values of the html at the top. When finished, copy what’s in the html box at the top of the page and use that as the Stout calendar feed.
It isn’t pretty, but it does work as long as the calendars are all public.