For the screensaver, find the .scr file in C:\Windows\System32\ then create a shortcut to it with the -s flag. For example:
Target: C:\Windows\system32\[screensaver].scr -s
For locking the workstation, use:
C:\Windows\System32\rundll32.exe user32.dll, LockWorkStation
Not sure you can do both in one, but I think you can set the screensaver to ask for a password afterwards, which has the same result.