<Component Id='c_WSService' Guid='*'>
    <File Id='f_WSService' Name='WSService.exe' Vital='yes' Source='..wssvrreleasewsservice.exe' />
    <ServiceInstall Id='WSService.exe' Name='WSService' DisplayName='[product name]' Type='ownProcess'
                    Interactive='no' Start='auto' Vital='yes' ErrorControl='normal'
                    Description='Provides local and remote access to [product name] search facilities.' />
    <ServiceControl Id='WSService.exe' Name='WSService' Start='install' Stop='both' Remove='uninstall' Wait='yes' />
</Component>

sc stop {name of your service}
sc start {name of your service}

'' This works.  It leaves the MSI in a state that tells you to reboot the PC, but you really don't need to.
Private Sub ProjectInstaller_BeforeInstall(sender As Object, e As System.Configuration.Install.InstallEventArgs) Handles Me.BeforeInstall

    Dim sEchoMessage As String = String.Empty
    sEchoMessage &= " & ECHO ******************       Please be patient      *******************************"
    sEchoMessage &= " & ECHO Pausing to stop and delete the previous version of the following service:"
    sEchoMessage &= " & ECHO " & ServiceInstaller1.ServiceName
    sEchoMessage &= " & ECHO -------------------------------------------------------------------------------"
    sEchoMessage &= " & ECHO After install is complete, you may see a message that says you need to reboot."
    sEchoMessage &= " & ECHO You may IGNORE this message - The service will be installed and running."
    sEchoMessage &= " & ECHO There is NO Reboot required."
    sEchoMessage &= " & ECHO *******************************************************************************"

    RunCommandCom("sc stop " & ServiceInstaller1.ServiceName & " & sc delete " & ServiceInstaller1.ServiceName & sEchoMessage, 15000)

End Sub

Private Sub RunCommandCom(command As String, mSecSleepAfterExecution As Integer)

    Using p As Process = New Process()
        Dim pi As ProcessStartInfo = New ProcessStartInfo()
        pi.Arguments = " /K " + command
        pi.FileName = "cmd.exe"
        p.StartInfo = pi
        p.Start()
        System.Threading.Thread.Sleep(mSecSleepAfterExecution)
        p.CloseMainWindow()
    End Using

End Sub