@Limun
I think you understood this post wrong.
My impression is, that he´s talking about converting PhpBB3 to Icy
Maybe, porting to SMF then to PhpBB2 and then to IP 1.3.0.53a
I think, thats the only way
here´s a link to the oficial
PhpBB3 to SMF converter
afterwards you can convert SMF to PhpBB2 and then to Icy
here´s a link to
SMF 1.1.x To PhpBB2 converter