I also tried Brucys Bass.Mod but the streaming functions are not yet implmented
They should be.
I've no major issues with streaming and BASS.
You might find using STREAMPROC is a bit of a problem using BlitzMax's standard GC, since it is called from a separate thread. There are ways around that, of course (An example of which is available in the GMEBass module).
Check the latest SVN version of the Bass module. It should have everything you need - written on Mac too, no less :-p