Setting up Lockscreen Calendar is extremely simple. Launch the app, tap the arrow icon at the bottom once and select one or more registered Google accounts of your choice. From within the screen that follows, you may alter the maximum number of Calendar events to be displayed and the interval after which the app rescans / updates said events. Tapping Update now immediately scans for any changes you may have made to your Calendar events, adjusting the ones displayed on the lockscreen accordingly.
Lockscreen Calendar supports all stock lockscreens, and can display upcoming meetings from multiple calendars. You can control how many upcoming appointments are shown, and how frequently the app updates what's shown on your desktop. This way if you're often double or triple-booked by coworkers who love to meet, or have meetings every hour or so, you can dial in the settings to show three or more items and update every hour.
Once installed, force the app to update at least once to pull in your calendar, and after that it'll update on the schedule you set. The app has a difficult time with recurring events, but the developer points out that the app is still a beta release and he's still working on it. Even so, it's fairly polished and worth a look if you have a full calendar.