The first poster was on the right track.
So, one quick way to create more columns is as follows:
1)create a new blog template,
2)then go to components\com_flexicontent\templates\new-blog-template\category.xml and add two more options for "intro_cols":
Code:
<param name="intro_cols" type="list" default="2" label="FLEXI_INTRO_COLS" description="FLEXI_INTRO_COLS_DESC">
			<option value="1">FLEXI_1_COL</option>
			<option value="2">FLEXI_2_COLS</option>
			<option value="3">FLEXI_3_COLS</option>
			<option value="4">FLEXI_4_COLS</option>
		</param>
 
3) While you are at the same folder, you need also to change category_items.php, at around line 276,
from:
Code:
<?php
	endif;
	if ($count > $leadnum || $this->limitstart != 0) :
		
?>
<ul class="introblock <?php echo ($this->params->get('intro_cols', 2) == 1) ? 'one' : 'two'; ?>">
 
to the following:
Code:
<?php
	endif;
	if ($count > $leadnum || $this->limitstart != 0) :
		//added to intercept more columns (see also css changes)
		$classnum = '';
		if ($this->params->get('intro_cols', 2) == 1) :
			$classnum = 'one';
		elseif ($this->params->get('intro_cols', 2) == 2) :
			$classnum = 'two';
		elseif ($this->params->get('intro_cols', 2) == 3) :
			$classnum = 'three';
		elseif ($this->params->get('intro_cols', 2) == 4) :
			$classnum = 'four';
		endif;
?>
<ul class="introblock <?php echo $classnum; ?>">
 
4) Lastly, you need to modify the file /css/category.css, and add lines for class "three" and class "four" e.g.
Code:
#flexicontent ul.introblock.three li {
	width: 30%;
}
#flexicontent ul.introblock.three li.even {
	margin-left: 1%
}
#flexicontent ul.introblock.four li {
	width: 23%;
}
#flexicontent ul.introblock.four li.even {
	margin-left: 1%
}
 
cheers!