Here's how I do it. On the desktop I have Outlook 2010 with the Hotmail connector installed, Windows Live Mail and the Blackberry Desktop Manager. The phone is a 9780. I would start with getting the phone syncing with the normal Outlook calendar first. Then install the Hotmail connector. That will give you access to your Hotmail calendar and Outlook calendar from within Outlook. Then in Outlook go to Account Settings and choose the Data Files tab. Set your Hotmail (or Live) account as the default. Restart Outlook. In the Calendars section of Outlook your Hotmail calendar should be the top one listed on the left, with the Outlook one just below it.
Then open the BB Desktop Manager and choose Organizer, Configure next to the Calendar, then Advanced. Go to the Folders tab and Add the Hotmail Calendar to the bottom section. Delete any other Calendar from the bottom I think. I'm kinda going on memory here. I think I had to close the BB Desktop manager and maybe reboot but it all started working.
So now when you enter something on the Phone, it updates the Hotmail Calendar in Outlook when you sync with the computer, which updates you Hotmail Calendar online, and then Windows Live Mail updates also when you start that.
Oh, and if you get an update to the BB Desktop manager it will wipe out all the settings and you have to go through most of it again. Took me hours to finally get it working again.