From Terminal23wiki
function CreateWinServices
{
#function creates services on local server for PCentral (or possibly others)
#strServiceName has no special chars, no spaces, and is also used as displayname
#strStartupType should be Automatic or Manual or Disabled
#strFilePath should be in local context to target server; absolute path
#strAccountName should be like DOMAIN\testaccount
param ([string]$strServiceName,
[string]$strFilePath,
[string]$strStartupType,
[string]$strAccountName,
[string]$strPlainPassword)
#may want to validate inputs and check if service already exists
#however, if it already exists, the error is non-terminating; the function will finish
$strSecurePassword = convertto-securestring $strPlainPassword -asplaintext -force
#if this securestring is passed into us, we just use it in the $cred = new-object below
$cred = new-object -typename System.Management.Automation.PSCredential -argumentlist $strAccountName,$strSecurePassword
new-service $strServiceName $strFilePath -startuptype $strStartupType -credential $cred
if ($strStartupType -eq "Automatic")
{start-service $strServiceName}
}