The following didn't parse
[x.y]::z -Param1 some_value
Is this even possible?
When you're calling .NET methods from PowerShell, you use C# style comma separated args in parens syntax e.g.:
[x.y]::z(some_value)
In PowerShell, named parameters are a feature of PowerShell commands (functions, advanced functions, scripts, cmdlets, workflows) only.