To change which scope of UIDs to kill you should alter the [#FROM:TO] part of the filter.
For example, you want to kill posts made by UIDs higher than 10k:
[#10000:*]
UIDs 1000 to 2000:
[#1000:2000]
and so on.
You can also exclude certain posters that you would like to "keep" by changing the "(^EXCLUSIONS HERE)" part of the filter. If you would like to exlude hirvi-o and stapler (maybe even devicenull =O ) from the carnage you would alter it to look like this:
(^hirvi-o|stapler)
separate names with a pipe "|".
Please note that I had to cripple it slightly so it wouldn't go on an uncontrolled killing spree. Because of this it will not work on HUGE posts.

Thanks to RedEyes for coming up with the idea.
URL = "www.genmay.net"
Active = False
Match = "(<table cellpadding=\"0\" cellspacing=\"0\" border=\"0\" bgcolor=\"\#000000\" width=\"100%\" align=\"center\"><tr><td> "
"<table cellpadding=\"4\" cellspacing=\"1\" border=\"0\" width=\"100%\"> "
"<tr> <td bgcolor=\"\#[0-9]+{6}\" width=\"175\" valign=\"top\" nowrap> <a name=\"post[0-9]+"><\/a> (<a name=\"newpost\"><\/a>)+{0,1} "
"<font face=\"arial, verdana, helvetica, sans-serif\" size=\"2\"><b><a href=\"member.php\?s=\&action=getinfo\&userid=([#FROM:TO])\2\" target=\"_blank\" style=\"text-decoration: none\"><font color=\"#FFFFFF\">(^EXCLUSIONS HERE)(*)\1</a></b></font></font><br>) "
"(<font face=\"arial, verdana, helvetica, sans-serif\" size=\"1\">*<br><br></font><br>)+{0,1} </td> "
"<td bgcolor=\"\#[0-9]+{6}\" width=\"100%\" valign=\"top\"> <font face=\"arial, verdana, helvetica, sans-serif\" size=\"1\"> <b></b></font> "
"* "
"</td> </tr> <tr> <td bgcolor=\"#[0-9]+{6}\" width=\"175\" height=\"16\" nowrap><font face=\"arial, verdana, helvetica, sans-serif\" size=\"1\"> "
"[0-9]+{2}-[0-9]+{2}-[0-9]+{4} <font color=\"#FFFFFF\">[0-9]+{2}:[0-9]+{2} (PM|AM)</font></font></td> "
"<td bgcolor=\"#[0-9]+{6}\" width=\"100%\" valign=\"middle\" height=\"16\"> "
"<table width=\"100%\" border=\"0\" cellpadding=\"0\" cellspacing=\"0\"> "
"<tr valign=\"bottom\"> "
"<td>*</td> "
"</tr> "
"</table> "
"</td> "
"</tr> "
"</table> "
"</td></tr></table> "
Replace = "<span style=\"font-family:arial; font-size:8pt;\">Here lies \"\1\", it had a UID of \2</span>"
