Andy,
What I want to do is feed drum trigger signals from an arduino board (a usb development board that lets you interface electronics to the computer) to a midi sequencer.
Why do you need to go through the computer for this? You can use the arduino's serial port to send and receive MIDI commands. It's really simple and there are tons of projects on the web that do exactly that.
I had a look at the following page from the alsa api reference:
http://www.alsa-project.org/alsa-doc/alsa-lib/seq.html
but I'm finding it a bit hard to follow - I'm looking for something a bit simpler with code examples to work through that will give me a way in to alsa midi programming.
Does anyone know of anything like this?
No, but that's the wrong page. For sending MIDI data you simply open the device (snd_rawmidi_open) and send your commands (snd_rawmidi_write).
Flo