> Orginal url:
> index.php?PHPSESSID=ijik080123u0j0u1j00&act=idx
> After
> index.php?act=idx

You can use the user defined structure + hide query string to get a similar
affect:

%h%p/%n%[act:_act-:::].%t would generate index_act-idx.html

<http://httrack.kauler.com/help/User-defined_structure>