Vista - How install a msi package on a remote computer with Powershell?

Hello,

the userguide delivered with powershell seems to have some errors.
For instance,
(Get-WmiObject -Class Win32_Product -Filter "Name='ILMerge'" -ComputerName .
).InvokeMethod("Uninstall",$null)
does not work, because
System.Management.ManagementObject#root\cimv2\Win32_Product] does not contain
a method with the name "InvokeMethod",
but
(Get-WmiObject -Class Win32_Product -Filter "Name='ILMerge'" -ComputerName .
).Uninstall()
does work.

(Get-WMIObject -ComputerName PC01 -List | Where-Object -FilterScript
{$_.Name -eq
"Win32_Product"}).InvokeMethod("Install","\\AppSrv\dsp\NewPackage.msi") does
not work for the same reason, but when I change this to
(Get-WMIObject -ComputerName PC01 -List | Where-Object -FilterScript
{$_.Name -eq "Win32_Product"}).Install("\\AppSrv\dsp\NewPackage.msi")
it reports an error 1619, which means it could not find the msi package.
But I know the package is there, because I can start it manually.

So what is wrong with my code?