copy customer/home.tpl to customer/home2.tpl
change your customer/home.tpl:
Code:
{if $main eq "catalog" && $current_category.categoryid eq "Custom_category_id"}
{include file="customer/home2.tpl"}
{else}
....Your current home.tpl content
{/if}
and edit home2.tpl
It will be displayed only for one custom category.