[FieldTrip] one EEG channel as trigger channel

[Steph]

Dear all,

I'm new to Fieldtrip and I've been reading through the tutorial and 
reference pages, but still not able to solve my problem:

there's raw EEG data, and one of the channels contains the trigger 
codes, i.e. it's not a trigger channel per se, so it can't be adressed 
via cfg.trialdef.eventtype.
I want to get through the preprocessing, but simply don't know how to 
properly define the event.

maybe writing my own trialfunction similar to 
http://fieldtrip.fcdonders.nl/example/detect_the_muscle_activity_in_an_emg_channel_and_use_that_as_trial_definition
might be the solution? I don't get the last few lines of the example 
script, though.

Hope you can help me make this work!
Best wishes