From the software update page http://support.vzw.com/pdf/system_update/droid_x.pdf
Here's how you do it:
http://alltechnews.org/mobile/how-to-use-multitouch-key-chording-on-droid-x-11338.html
To use multi chording, you have to press and hold down the “?123” key, soon another keyboard for numbers and signs will appear. Drag your finger, without lifting from the keyboard, to the desired key and let go. Alphabetic keyboard will re-appear as soon as you raise your finger.
From https://supportforums.motorola.com/message/450079#
Multi-Touch Key-Chording:
New ability to enter numbers and symbols with keyboard shortcut combos,
without having to change to the numeric keyboard mode.
Here's how you do it:
http://alltechnews.org/mobile/how-to-use-multitouch-key-chording-on-droid-x-11338.html
To use multi chording, you have to press and hold down the “?123” key, soon another keyboard for numbers and signs will appear. Drag your finger, without lifting from the keyboard, to the desired key and let go. Alphabetic keyboard will re-appear as soon as you raise your finger.
From https://supportforums.motorola.com/message/450079#