Hello, I am a very, very newbie but I just came accross this same problem today and made it work . . . not easy . . . here is what I did.
$chk = "CHECKED";
$Q = "<img src=http://carsguam.com/img/check.gif>";
if ($a["op_ps"]) { $cb1=$chk; } else { $cb1=" "; }
if ($a["op_pb"]) { $cb2=$chk; } else { $cb2=" "; }
if ($a["op_ab"]) { $cb3=$chk; } else { $cb3=" "; }
if ($a["op_alb"]) { $cb4=$chk; } else { $cb4=" "; }
if ($a["op_tc"]) { $cb5=$chk; } else { $cb5=" "; }
if ($a["op_ac"]) { $cb6=$chk; } else { $cb6=" "; }
if ($a["op_sr"]) { $cb7=$chk; } else { $cb7=" "; }
if ($a["op_cc"]) { $cb8=$chk; } else { $cb8=" "; }
if ($a["op_pw"]) { $cb9=$chk; } else { $cb9=" "; }
if ($a["op_pl"]) { $cb10=$chk; } else { $cb10=" "; }
if ($a["op_ls"]) { $cb12=$chk; } else { $cb12=" "; }
if ($a["op_fl"]) { $cb13=$chk; } else { $cb13=" "; }
if ($a["op_as"]) { $cb14=$chk; } else { $cb14=" "; }
if ($a["op_iw"]) { $cb15=$chk; } else { $cb15=" "; }
then just:
<input type="checkbox" name="op_iw" value="<img src=img/check.gif>" <? echo $cb15 ?>>
This may be stupid, but it is simple and it worked for me.