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Registry: HKEY_CURRENT_USER\Control Panel\Mouse

The values under the registry key HKEY_CURRENT_USER\Control Panel\Mouse allows to change the behavior of the mouse (aka pointer).

MouseSensitivity

The value MouseSensitivity determines the speed (or sensitivity) of the mouse: from 1 (slowest) to 20 (fastest). The default is 10.
In cmd.exe, this setting can be changed with reg.exe: 
reg add "HKEY_CURRENT_USER\Control Panel\Mouse" /t REG_SZ /v MouseSensitivity /d "10" /f
In PowerShell, this setting can be queried and set like so: 
(get-itemProperty 'HKCU:\Control Panel\Mouse' ).MouseSensitivity
set-itemProperty 'HKCU:\Control Panel\Mouse' -name MouseSensitivity -value 20
See also this simple PowerShell script to change the speed of the mouse.

SendMessage to have changes take effect

Apparently, the WinAPI function SendMessage(HWND_BROADCAST, WM_SETTINGCHANGE, 0, "Environment") should be executed in order for the changes to take effect.

See also

The lines to be scrolled when using the mouse wheel are adjusted in the value WheelScrollLines under HKEY_CURRENT_USER\Control Panel\Desktop.
Opening the mouse control panel with rundll32.exe
HKEY_CURRENT_USER\Control Panel

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