How do you access the Boinccmd? Is it a separate program or in the boinc manager?

When you install BOINC, boinccmd is an additional executable file that is installed as part of the package.

The rest of this answer will be applicable to Windows only. You don't say which operating system you use - if it's something else, my apologies for wasting your time.

When BOINC is installed on Windows, it's divided into two parts - a program directory and a data diectory. For boinccmd, you need to find the program directory. By default, this will be C:\Program Files\BOINC

Navigate to this directory in Windows Explorer and - assuming you are running Windows 7 or later - right-click on the folder name in the left-hand pane while holding the shift key. Holding the shift key while right-clicking will add "Open command windows here" to the context menu.

That's the one you want. Click the command window to give it focus (for some reason, Windows doesn't do this automatically), and you're ready to go - type boinccmd followed by whatever commands you need from The boinccmd command-line tool