Rather than just calling IBM's command line tools or 3rd party command line tools IBM have built a Cmdlet for managing WebSphere MQ, which is available from IBM MO74: WebSphere MQ - Windows Powershell Library. When it was first launched Microsoft blogged about it at IBM Releases PowerShell Cmdlets to Manage WebSphere MQ - Windows PowerShell Blog - Site Home - MSDN Blogs. However not everyone has had a smooth experience with it as can be see MQSeries.net :: View topic - Powershell - Support Pac MO74.
Owing to pressure of time I ended up using Start-Process to launch the IBM IH03: WebSphere Message Broker - Message display, test & performance utilities - United States tools.