/Library/StartupItems/
/System/Library/StartupItems/
などというのは 古いっていう話 ? でも使い方: CreatingStartupItems が書いてある。

d176:~ makoto$ cd
d176:~ makoto$ pwd
/Users/makoto
d176:~ makoto$ mkdir CvsRoot
d176:~ makoto$ cvs -d ~/CvsRoot init
d176:~ makoto$ mkdir CvsRoot/Library
d176:~ makoto$ cvs -d ~/CvsRoot co Library
cvs checkout: Updating Library
? Library/.localized
? Library/Address Book Plug-Ins
? Library/Application Support
..... (omitted) ....
? Library/Sounds
? Library/StartupItems
d176:~ makoto$ cd Library/
d176:~ makoto$ cvs add StartupItems
Directory /Users/makoto/CvsRoot/Library/StartupItems added to the repository
d176:~/Library makoto$

＠ ついでに /etc も: