Ctrl wan't in 3.1, one pressed Shift + f8 (I think that was the key) and then space to select and arrows moved the focus without changing selection. I can't remember how one changed back to normal selection mode.
Here we go. From 3.1's Help
Using the Keyboard to Select Files and Directories
You can use the keyboard to select one or more directories or files. Before you can select items, they must be visible in the directory window.
To select a file or directory
Use the following keys to select a file or directory.
Press To select
UP or DOWN ARROW A file or directory above or below the current selection.
END The last item in the list.
HOME The first item in the list.
PAGE UP The item at the top of the previous screen.
PAGE DOWN The item at the bottom of the next screen.
A character The next item that begins with that letter or number.
To select two or more items in sequence
1 Use the arrow keys to move to the first file or directory you want to select.
2 Press and hold down SHIFT while you select the remaining items in the group.
To select two or more items out of sequence
1 Use the arrow keys to move to the first file or directory you want to select.
2 Press and release SHIFT+F8. The selection cursor begins to blink.
3 Move to the next item you want to select.
4 Press the SPACEBAR to select each file or directory.
5 Press and release SHIFT+F8 when you finish selecting files.
To cancel a selection
1 Press and release SHIFT+F8 so that the selection cursor begins to blink.
2 Move to the selection you want to cancel, and then press the SPACEBAR.
3 Press and release SHIFT+F8 when you finish canceling selections.