The code for 4.1.7 would be different, I believe:
Code for auth.php before ?>
Code:
$userinfo = func_query_first("SELECT login,firstname,lastname,membershipid FROM $sql_tbl[customers] WHERE login='$login'");
$smarty->assign("userinfo", $userinfo);
Code for use in template:
Code:
{* Where "X" is the numeric membershipid *}
{if $userinfo.membershipid eq "X"} Show Text{/if}