Does the D700 allow for once the AE/L button is pressed to lock and hold the setting after releasing the AE/L? I have searched all the different functions but have not been able at this point to find the setting or combination to allow for this function.
It is very easy. You can set the behaviuor of AE-L/AF-L button in the f7 (Assign AE-L/AF-L button) custom settings menu.
For your purpose select f7 and then "AE-L/AF-L button press" submenu. In the submenu select "AE lock (Hold)" or "AE lock (Reset on release)" setting. Both lock the AE value when AE-L/AF-L button is being pressed, but the first setting holds the value until you press AE-L/AF-L again, while the second one holds the value until you press shutter release or until the meter switches-off or you press AE-L/AF-L again. Very useful seting, I use it all the time.