I had the same problem.
I work in an environment where I am not considered mobile enough to warrant a company Blackberry. However I have my own and like to keep my calendar with me.
I went online to RIM’s (Reasearch In Motion) and downloaded their Desktop Manager ver 4.2.2 and that simply allows you to set up a path to your desktop email and calendar in Lotus Notes and code in your password so when you connect via a USB cable the password is synched and the blackberry downloads the Calendar.
Hope this helps.
If you have designer or manager access to your mail file you can buy some software from Martin-Scott www.martinscott.com that bascially enables Blackberry push mail and sync without the need for a BES. It’s a template update to your mail file with some agents that run to send you messages and sync your calendar can contacts. I’ve used it in the past, it is quite nice.