function SetCustomForms-InContentType()
    {
        param(
            [Parameter(Mandatory=$true)][string]$url,
            [Parameter(Mandatory=$false)][System.Net.NetworkCredential]$credentials,
            [Parameter(Mandatory=$true)][string]$ContentTypeName
        )

        begin{
            try
            {
                #get Client Object
                $Context = New-Object Microsoft.SharePoint.Client.ClientContext($url)
                $Context.Credentials = $Credentials

                #Load web object
                $web = $Context.Web
                $site = $context.Site
                $Context.Load($web)
                $Context.Load($site)
                $Context.ExecuteQuery()

            }
            catch
            {
                Write-Host "Error while getting context. Error -->> "  + $_.Exception.Message -ForegroundColor Red
            }
        }
        process{
            try
            {

                $contentTypes = $Context.Site.RootWeb.ContentTypes
                $Context.Load($contentTypes)
                $Context.ExecuteQuery()
                $contentType = $contentTypes | Where {$_.Name -eq $ContentTypeName}

                $contentType.EditFormUrl = "Your Custom URL"
                $contentType.NewFormUrl = "Your Custom URL"
                $contentType.DisplayFormUrl = "Your Custom URL"


                $contentType.Update()
                $Context.Load($contentType)
                $Context.ExecuteQuery()
            }
            catch
            {
                Write-Host ("Error -->> " + $_.Exception.Message) -ForegroundColor Red
            }
        }
        end{
            $Context.Dispose()
        }
    }


    $credentials = Get-Credential
    $Url = 'http://YourSite'

    SetCustomForms-InContentType $Url $credentials "Your Content Type Name"