You can program the ARP notes (chord) on one trigger by holding the trigger down and then using the ARP sequence editor. Arp MODE needs to be set to KEY, I believe. (see page 63 in the manual)

This will make your arp start when the trigger has been reached in the sequencer (all notes live on one trigger). The you can COPY and PASTE that arp trigger in different places, and use a NOTE OFF trig to stop the arp.

I hope that helps.