In case those links don't work exactly right (those posts were for 1.3.x, and if you're using 1.4.x it may not work correctly), this is copied from the search page in Coppermine:
<form method="post" action="thumbnails.php" name="searchcpg">
<!-- Start standard table -->
<table align="center" width="60%" cellspacing="1" cellpadding="0" class="maintable">
<tr>
<td class="tableh1" colspan="1">Search the file collection</td>
</tr>
<tr>
<td class="tableb" align="center" >
<input type="text" style="width: 80%" name="search" maxlength="255" value="" class="textinput" />
<input type="submit" value="search" class="button" />
<input type="hidden" name="album" value="search" />
</td>
</tr>
<tr>
<td class="tableb">
<table align="center" width="60%">
<tr>
<td>Search in:</td>
<td align="center">Age:</td>
</tr>
<tr>
<td><input type="checkbox" name="title" id="title" class="checkbox" checked="checked" /><label for="title" class="clickable_option">Title</label></td>
<td align="right">Newer than <input type="text" name="newer_than" size="3" maxlength="4" class="textinput" /> days</td>
</tr>
<tr>
<td><input type="checkbox" name="caption" id="caption" class="checkbox" checked="checked" /><label for="caption" class="clickable_option">Caption</label></td>
<td align="right">Older than <input type="text" name="older_than" size="3" maxlength="4" class="textinput" /> days</td>
</tr>
<tr>
<td><input type="checkbox" name="keywords" id="keywords" class="checkbox" checked="checked" /><label for="keywords" class="clickable_option">Keywords</label></td>
<td> </td>
</tr>
<tr>
<td><input type="checkbox" name="owner_name" id="owner_name" class="checkbox" /><label for="owner_name" class="clickable_option">Owner name</label></td>
<td align="right"><select name="type" class="listbox">
<option value="AND" selected="selected">Match all words (AND)</option>
<option value="OR">Match any words (OR)</option></select>
</td>
</tr>
<tr>
<td><input type="checkbox" name="filename" id="filename" class="checkbox" /><label for="filename" class="clickable_option">Filename</label></td>
<td> </td>
</tr>
<tr>
<td> </td>
<td> </td>
</tr>
</table>
</td>
</tr></table>
<!-- End standard table -->
</form>
If you aren't using your theme's style.css on that page, you'll have to edit or remove the class statements. If thumbnails.php isn't in the same directory as your html file, you'll have to edit the url. Otherwise it should work.