As promised. Please follow the instructions below. Note: I reverted back to 32x32 images
Create a new "custom fields for forum content", field type "An uploaded picture"
Give it whatever title you want.
I am assuming this is your 1st custom field for forum content, and will be referring to the ID as 0
Save and close the custome field page now.

Go to your respective cns.css and add the following to the bottom:

/* FORUM ICONS */
.cns_no_new {
opacity: 0.5;
}
/*end FORUM ICONS*/

The above will set the opacity level of you read forum images. Change this value to suit your needs.

Next the template edit.

Open your respective CNS_FORUM_IN_GROUPING.tpl

Find

<td class="cns_forum_new_post_indicator cns_column1"> <img width="32" height="32" title="{LANG_NEW_POST_OR_NOT*}" alt="{LANG_NEW_POST_OR_NOT*}" src="{$IMG*,cns_general/{NEW_POST_OR_NOT*}}" /> </td>

And replace it with (I am sure there is a neater way of doing this, but hey, it works)

     {+START,IF_EMPTY,{$CATALOGUE_ENTRY_FOR,forum,{ID},0}}     
    <td class="cns_forum_new_post_indicator cns_column1 cns_no_new">
    <img width="32" height="32" title="{LANG_NEW_POST_OR_NOT*}" alt="{LANG_NEW_POST_OR_NOT*}" src="{$IMG*,cns_general/{NEW_POST_OR_NOT*}}" />
    </td>
    {+END}    
    
    {+START,IF_NON_EMPTY,{$CATALOGUE_ENTRY_FOR,forum,{ID},0}}
    
    {+START,IF,{$EQ,{LANG_NEW_POST_OR_NOT*},No new posts}}
    <td class="cns_forum_new_post_indicator cns_column1 cns_no_new">
    <img width="32" height="32" title="{LANG_NEW_POST_OR_NOT*}" alt="{LANG_NEW_POST_OR_NOT*}" src="{$BASE_URL}/{$CATALOGUE_ENTRY_FIELD_VALUE_PLAIN,{$CATALOGUE_ENTRY_FOR,forum,{ID}},0}" />
    </td>
    {+END}
    
    {+START,IF,{$EQ,{LANG_NEW_POST_OR_NOT*},New posts}}
    <td class="cns_forum_new_post_indicator cns_column1">
    <img width="32" height="32" title="{LANG_NEW_POST_OR_NOT*}" alt="{LANG_NEW_POST_OR_NOT*}" src="{$BASE_URL}/{$CATALOGUE_ENTRY_FIELD_VALUE_PLAIN,{$CATALOGUE_ENTRY_FOR,forum,{ID}},0}" />
    </td>
    {+END}


Now you should be able to go to you forum, upload a 32x32 image and have it show like my 1st post.

If anyone has any issues please let me know.

​Enjoy