Sasha,

In products that use the DS'4x0 i've fully included the small circuit required for ISP (and this has already saved headaches when the occasion to be able to provide a product variant to serve a specific customer requirement reared it head).

In the case of the little projects i have built for concept testing or just plain diddling i have only included a little header and built the "programming circuit" as a stand-alone board which i just connect to the circuit i need to update.

This is easy to do because of the SIO transfer/bootloader characteristic of the DS'4X0 series. The relatively low data rate of this SIO transfer allows reasonable wire lengths and equally simple interconnect.

regards,
p