[Theater]

Simply add all the usergroups IDs separated by a comma. You'll only have to do it once unless you add a usergroup of course.

So from a step listed in the background postbit mod (linked above):

<if condition="is_member_of($post, #)">
<td class="postbit" width="175" style="border: $stylevar[cellspacing]px solid $stylevar [tborder_bgcolor]; border-top: 0px; border-bottom: 0px id="td_post_$post[postid]">
<else />
<td class="alt2" width="175" style="border: $stylevar[cellspacing]px solid $stylevar[tborder_bgcolor]; border-top: 0px; border-bottom: 0px"></if>

So where the red # is, add in your usergroups. Default IDs:

1 = Unregisted / Not Logged In
2 = Registered
3 = Users Awaiting Email Confirmation
4 = (COPPA) Users Awaiting Moderation
5 = Super Moderator
6 = Administrators
7 = Moderators
Plus whatever custom usergroup ID you have..

So to add them all:

<if condition="is_member_of($post, 1,2,3,4,5,6,7)">
<td class="postbit" width="175" style="border: $stylevar[cellspacing]px solid $stylevar [tborder_bgcolor]; border-top: 0px; border-bottom: 0px id="td_post_$post[postid]">
<else />
<td class="alt2" width="175" style="border: $stylevar[cellspacing]px solid $stylevar[tborder_bgcolor]; border-top: 0px; border-bottom: 0px"></if>

I'm not sure if there is a PHP wildcard, but that above should work fine for you.