You can assign speed dial buttons on the VVX 410 to any buttons that are not already assigned a function like Presence. To do this, follow these steps:
Press the menu button.
Go to Directories.
Select option 1 Contact Directory and press add.
Enter first and last name as well as the phone number in the contact field.
Scroll down to the "Favorite Index" field and enter the button number you wish to assign the entry to. Numbering starts at 1 and continues up for the number of free buttons you have on the phone. So, 1 is the first available button on the phone after any presence / line keys that are already assigned.
Save the entry and you should see the button on the phones home screen. A single push of the button will auto-dial the number entered.