Adaptor plates have been out and a company is about to come out w/ an intake. As for long tubes, those are being worked on but the 4.6 headers will fit, but need to be modified. If your interested, there's no better place for info on the swap than here:
Anyone intrested in 5.4L swaps, in here. Need you to opine. - Mustang Forums
I understand that it's very long but any questions that you have (including costs) are in there, some where.