You can use 

    apply_filters('show_password_fields', true) )
    add_filter('show_password_fields','youfunction',10,1);
    function youfunction($return)
    {
    	?>
    	<tr>
    					<th><label for="gender">Gender</label></th>
    					<td>
    						
    						<label><input type="radio" name="w4p_user_gender"  value="male" class="regular-radio"  />Male</label>
    						<label style="margin-left:10px"><input type="radio" name="w4p_user_gender"  value="female" class="regular-radio"  />Female</label><br/>
    						<span class="description">Please select your Gender.</span>
    					</td>
    				</tr>
    	<?php
    	return true;
    }

this filter to add your fields.
I don't know it's is a good idea or not but works for me :).