It seems no one really knows this service for english speakers. I suggest just calling up schools and see if they can teach you in english.

A short list can be found:
http://www.bfu.ch/beratung_sport/inline/inline_d.pdf

Another:
ISW-Sports / Die Profis für Inline-Skating Nordic Walking Langlauf


There would be more listed under google. Try plugging this line in:
inline schule zurich site:.ch

Good luck.