If you want to run any of the Exchange PowerShell commands from a standard PowerShell environment then you simply need to add in the following line in order to run it as if it is an Exchange Management Console:
For example, the script below will output the size of the Exchange Databases to a file and can be run as a scheduled task:
Get-MailboxDatabase –Status | fl name, databasesize | out-file C:dbsize.txt
What we can do then is save the above script to a .ps1 file and then edit the action to start PowerShell.exe and put the arguments as the script that you want to run:
This can be set up with the usual Scheduled Task settings and with the PowerShell snap-in for Exchange added in should be able to use the Exchange PowerShell commands.