If by "changing the size of the mouse using another command in the terminal", you mean that you set the System Preferences value (i.e. using 'defaults' command), then you could either log out and log back in, or it may be a bit tedious -- see this answer: How to programatically change the cursor size on a Mac
If all you need to do is to change a mouse cursor size system-wide, you can use UI scripting (as suggested in the answer I linked). The command to execute would be:
osascript -e '
tell application "System Preferences"
reveal anchor "Seeing_Display" of pane id "com.apple.preference.universalaccess"
end tell
tell application "System Events"
set theSlider to slider "Cursor size:" of group 1 of window 1 of application process "System Preferences"
set stash to value of theSlider
set value of theSlider to SIZE_OF_THE_CURSOR
stash
end tell'
Note that you need to "enable assistive access" to osascript:
http://jacobsalmela.com/bash-script-enable-access-assistive-devices-programmatically-os-x-mavericks-10-9-x-simulate-keystrokes/
"is not allowed for assistive access" error when running AppleScript from Java