How to manually add a new user account by command line in Mac OSX Snow Leopard

sh-3.2# dscl . -create /Users/svnuser
sh-3.2# dscl . -create /Users/svnuser UserShell /bin/bash
sh-3.2# dscl . -passwd /Users/svnuser passwd
sh-3.2# dscl . -create /Users/svnuser RealName SvnUser
sh-3.2# dscl . -create /Users/svnuser UniqueID 510  
sh-3.2# dscl . -create /Users/svnuser PrimaryGroupID 80
sh-3.2# dscl . -create /Users/svnuser NFSHomeDirectory /Users/svnuser
sh-3.2# cp -R /System/Library/User\ Template/English.lproj/ /Users/svnuser
sh-3.2# chown -R svnuser:staff /Users/svnuser

Refer from :

http://serverfault.com/questions/20702/how-do-i-create-user-accounts-from-the-terminal-in-mac-os-x-10-5

http://osxdaily.com/2007/10/29/how-to-add-a-user-from-the-os-x-command-line-works-with-leopard/