You can just install three modules from SQL Feature pack that provides the SQLPS functionality and use it without Invoke. Get and install in this order:
Microsoft® System CLR Types for Microsoft® SQL Server® 2012 Microsoft®
SQL Server® 2012 Shared Management Objects Microsoft® Windows
PowerShell Extensions for Microsoft® SQL Server® 2012
from here. After this you can run them localy and access remote SQL servers back to SQL 2000. Read here for some help.