it would be nice if H2 could send CC midi messages to external apps/hardware
maybe a new type of instrument can be created (a 'CC/Sysex instrument') that can also be added to a drumkit and that allows you to place notes in a pattern just like you place a note on a regular instrument.
the only difference would be that you need some way of entering a totally arbitrary midi message string. A simple 'enter midi message here' popup window would do > it's up to the user to make sure that the midi message he enters is valid.

see http://hydrogen.popez.org/hcms/node/1913#comment-57548