hint: sitemap is called by body-switch template, change the call to the custom nested-sitemap template

nested-sitemap()

DIV id "info-div"
  DIV class "infoText"
    WITH-OBJECT :index
      DIV id "sitemap-main-contents"
        WHEN @contents
          CALL :nested-sitemap-section 
            @contents
        WHEN @price
          DIV id "sitemap-item"
            WITH-LINK TO id
              TEXT @name
              LINEBREAK 

nested-sitemap-section(contents)

FOR-EACH-OBJECT contents
  DIV 
    WHEN @contents
      DIV id "sitemap-contents"
        FONT size "+1"
             face @text-font
          TEXT @name
          TEXT "<hr width=\"200px\">"
          CALL :nested-sitemap-section 
            @contents
    WHEN @price
      DIV id "sitemap-item"
        WITH-LINK TO id
          TEXT @name
          LINEBREAK

use this RTML template to create a nested, heirarchical sitemap for your Yahoo! Store

Heirarchical SiteMap RTML Template for Yahoo! Stores

Other