Say you have both FAA and JAA IR's and you have a gap of about 8 months without doing any approaches etc but then in the next few months you do the 6 required approaches using your JAA IR, is your FAA IR now current again?
As far as I'm aware yes that it OK from the FAA's point of view since the FARs make no mention of it having to be done while exercising the privileges of your FAA IR or it having to be in an N-reg aircraft. All the previous threads about whether you can do this with either JAA IR or IMC rating seem to say the same.