From time to time we are asked about accessing the PDF Conversion Service from PowerShell. Although we have no sample code, PowerShell is similar to other .NET environments - for which we do provide plenty of code samples.
Although you can use PowerShell's built in web services facilities using the New-WebServiceProxy command. It is much easier to use the pre-generated proxy DLL that ships alongside our software.
In the folder where the Conversion Service has been deployed to (See the Muhimbi Document Converter/Open Installation Folder shortcut in the Windows start menu) you will find the Muhimbi.DocumentConverter.WebService.Client.dll. This DLL contains up to date proxies for the entire web service. For details about how to use the various objects and methods see this KB Article.