Hi HPMAN,
yes, the bios call method would be desirable... but, as always, the ASM code is the problem...

According to the wiki I think I need to:
1) change "_CDDA_FLAG= 0" in file "crt0_cd.s" to "_CDDA_FLAG= 2" ?
2) call the CDDA routine via ASM

__asm__ ("jsr 0xC0056A");

3) But how to write the command / track number to register D0? As a word? For instance command 04, track no 02 would be 0x0402?

__asm__ ("move.w d0, 0x0402");