kj --
To do what you want, you need to use a little trick. Here's how to do it:
1. Apply the Gantt Chart view.
2. Right-click on the Duration column header and select Insert Column from
the shortcut menu.
3. In the Column Definition dialog, select the Marked column and then click
the OK button.
4. In the Marked column, set the value to Yes for every task you want to
baseline.
5. On the far right end of the Formatting toolbar, click the AutoFilter
button.
6. Click the AutoFilter arrow button on the Marked column and select the
Yes value.
The preceding step will display only the tasks whose value you set to Yes in
the Marked column.
7. Click the Select All button (upper left corner above the task list) to
select all displayed tasks.
8. Click Tools - Tracking - Save Baseline (or Set Baseline in Project
2007).
9. In the dialog, choose the "Selected tasks" option and click the OK
button.
10. Click the AutoFilter button again to disable the AutoFilter.
The above process will save the baseline for only the selected tasks and now
you can exceed the limit imposed by manually selecting the tasks using the
Control key. Hope this helps.