Using curl via the system command deploys via the coder without any problems. Not sure if it the most sensible way but does enable updating of a thingSpeak channel and is very easy to implement. Example code below adds random number to field 1 of channel.
% raspberry pi object
r = raspi();
% log file
fid = fopen( 'logFile.log', 'w' );
% write random number to thingSpeak channel
v = rand;
commandStr = [ 'sudo curl -s "https://api.thingspeak.com/update.json?api_key=<your api key here>&field1=' sprintf( '%f', v ) '"' ];
result = system( r, commandStr );
% log command
fprintf( fid, '%s \n', commandStr );
% log result
fprintf( fid, '%s \n', result );
% close log
fclose( fid );
