Update-RegistryFile.ps1

function Update-RegistryFile {
    <#
    .SYNOPSIS
        Updates a registry file.
    .DESCRIPTION
        Line break and certain characters will not import from standard registry files (even if export works).

        This function replaces any entry with line breaks with a hex value representing the string.
    #>

    [CmdletBinding()]
    param (
        # The path to the file to read and convert.
        [Parameter(Mandatory, ValueFromPipeline)]
        [ValidateScript( { Test-Path $_ -PathType Leaf } )]
        [Alias('PSPath')]
        [String]$Path,

        # The output path. By default the new file is created  derived from the original.
        [String]$OutputPath
    )

    process {
        $content = Get-Content -Path $Path -Raw
        [Regex]::Matches($content, '(?<=^|\r?\n)"([^"]+)"="([^"]*\r?\n[^"]+)"') |
            Sort-Object Index -Descending |
            ForEach-Object {
                $newValue = '"{0}"=hex(1):{1}' -f @(
                    $_.Groups.Item(1).Value
                    [System.Text.Encoding]::Unicode.GetBytes((
                        $_.Groups.Item(2).Value -replace '\r' -replace '\\\\', '\'
                    )).ForEach{ '{0:x2}' -f $_ } -join ','
                )

                $content = $content.Remove(
                    $_.Index,
                    $_.Value.Length
                ).Insert(
                    $_.Index,
                    $newValue
                )
            }

        if (-not $OutputPath) {
            $OutputPath = '{0}.Updated{1}' -f @(
                [System.IO.Path]::GetFileNameWithoutExtension($Path)
                [System.IO.Path]::GetExtension($Path)
            )
        }

        Set-Content -Path $OutputPath -Value $content -NoNewline
    }
}