How to load PowerShell Module from custom script on vNext build agent?

I am using the standard TFS vNext build step to execute a PowerShell script. Inside the script I am trying to take advantage of some of the functions within the standard TFS Agent modules.

Listed here: http://blog.majcica.com/2015/11/14/available-modules-for-tfs-2015-build-tasks/

I have seen the following two lines in many PowerShell scripts found in the build steps:

Import-Module "Microsoft.TeamFoundation.DistributedTask.Task.Internal"
Import-Module "Microsoft.TeamFoundation.DistributedTask.Task.Common"

I have tried to use the same lines in my script, however I get the error:

VERBOSE: Loading module from path 
'C:\TFS2015-Agent\Agent1\agent\agent\worker\Modules\Microsoft.TeamFoundation.DistributedTask.Task.Common\Microsoft.TeamFoundation.DistributedTask.Task.Common.dll'.
Import-Module : Could not load file or assembly 'Microsoft.TeamFoundation.DistributedTask.Agent.Interfaces, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. 
The system cannot find the file specified.
At C:\tfsVnBw1\3\s\Configuration\BuildScripts\CommonFunctions.ps1:25 char:5
+ Import-Module "Microsoft.TeamFoundation.DistributedTask.Task.Common" - Error ... + CategoryInfo : NotSpecified: (:) [Import-Module], FileNotFoundException + FullyQualifiedErrorId : System.IO.FileNotFoundException,Microsoft.PowerShell.Commands.ImportModuleCommand

If I try not to import, it writes something like:

The 'Find-Files' command was found in the module 'Microsoft.TeamFoundation.DistributedTask.Task.Common', 
but the module could not be loaded. For more information, run 'Import-Module Microsoft.TeamFoundation.DistributedTask.Task.Common'. 
At C:\tfsVnBw1\3\s\Configuration\BuildScripts\CommonFunctions.ps1:71 char:16
+ $files = @(FindFiles $filePattern)
+ ~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (Find-Files:String) [FindFiles], CommandNotFoundException + FullyQualifiedErrorId : CouldNotAutoloadMatchingModule

Is it not possible to use the Modules from 'normal' PowerShell scripts and not only from PowerShell scripts registered as an actual build step?

Try to specify build agent’s module path, such as:

 # Import the Task.Common and Task.Internal dll that has all the cmdlets we need for Build
$agentWorkerModulesPathRoot = "$($env:AGENT_HOMEDIRECTORY)\agent\worker"
$agentDistributedTaskInterfacesModulePath = "$agentWorkerModulesPathRoot\Microsoft.TeamFoundation.DistributedTask.Agent.Interfaces.dll"
$agentWorkerModulesPath = "$($env:AGENT_HOMEDIRECTORY)\agent\worker\Modules"
$agentDistributedTaskCommonModulePath = "$agentWorkerModulesPath\Microsoft.TeamFoundation.DistributedTask.Task.Common\Microsoft.TeamFoundation.DistributedTask.Task.Common.dll"

Write-Host "Importing VSTS Module $agentDistributedTaskInterfacesModulePath"
Import-Module $agentDistributedTaskInterfacesModulePath
Write-Host "Importing VSTS Module $agentDistributedTaskCommonModulePath"
Import-Module $agentDistributedTaskCommonModulePath