function StringToHex($i) {
    $r = ""
    $i.ToCharArray() | foreach-object -process {
        $r += '{0:X}' -f [int][char]$_
        }
    return $r
    }
$sshKey = 'ssh pub key here lolz'
$sshPublicKey = StringToHex -i $sshKey
$UsernameAddTo = "TestingAccount"
Set-ADUser $UsernameAddTo -Replace @{sshPublicKey="$sshPublicKey"}