One company which provides instructor renewal seminars is on the link below. I should point out, before I get pilloried for advertising, that there are other companies who offer seminars as well. I attended a seminar organised by this company when I did my last renewal and found it very interesting.
For Whirly: On my renewal, there were rotary instructors as well. The only difference was that when it came to doing the presentation, it was rotary-specific (describing vortex ring and how to avoid it from what I remember). All the rest was generic. When I did it three years ago it was about £250 for the two days excluding accommodation.
http://www.flightexaminers.com/seminars1.htm