[LAD] alsa sequencer and sysex editing

hello ") Ok, I am writing a remote and SysEx-editor for e-mu synthesizers (http://ppcontrol.sf.net). I am asking for help on how to use the alsa sequencer the way it was intended to be used for this kind of application. You know, there are so many options and flags and stuff to be used and I feel a little lost. Basically I send a lot of SysEx messages and need to make sure to catch all the answers. My current implementation is as following: I have a single sequencer (duplex, nonblocking), a queue and two ports: one with read and one with write caps. To send a SysEx command I just queue an event with that message. (So far so good?). Now I just wait for an constant time (usleep) before I check the input queue. Problem: if the time is too short, i would have missed the answer, if I wait to long I waste time. My question is: how would I make sure to catch all answers from the device without using a thread and without just waiting for an constant time before I check if there is an answer( which is alo not very fail save, a message might take a little longer if there is traffic on the midibus)? Thank you. Jan