1) Download Input driver for Dell Latitude E6410 from: https://downloads.dell.com/input/DRVR_WIN_R310070.EXE
If the link is broken, do a search on the file name: DRVR_WIN_R310070.EXE
2) Install the driver package & reboot
If the installer doesn't work, do a manual update of the driver from Device Manager on the PS/2 Compatible mouse. When updating the driver, choose "Let me pick the driver" and point to the folder where the driver package has been extracted. (you can use 7-zip to extract the package if you need to)
3) Go to the Windows 10 Mouse Settings (Search -> "Mouse" -> Click Mouse Settings
4) On the Mouse Settings page, Click "Additional Mouse Options"
5) The first tab should be the Dell DuoPoint tab (or whatever it was called). At the bottom, Click "Click to change Dell Touchpad settings"
6) On the Touchpad Sensitivity tab, lower "Touch Pressure". I found this helps the responsiveness of the touchpad
7) Save the settings
8) Click the Pointer Stick icon (middle icon; blue button surrounded by keyboard)
9) On the Sensitivity Tab, Disable the Pointstick
10) Click the Buttons Tab and Disable the Pointstick Buttons
11) Save the settings
12) Test the touchpad and pointstick buttons and done!
I ran into a problem where the touchpad quit working after testing, so I reboot the computer. After the reboot, I didn't have any more problems what-so-ever so keep that in mind that a reboot might be necessary
Hope that helps you get the touchpad working on your Dell Latitude E6400 running Windows 10!