As soon as you begin time-stretching real-time audio it is, of course, no longer real-time audio. For this reason, time-stretching opcodes that use a buffer (e.g. GEN01) are still valid - you just need to be writing the live audio stream into the GEN01 table. Another alternative it to use an f-sig buffer. Inevitably you will need to build some code around the main opcode in order to get this to work and there are a couple of Cabbage examples that do this: TimeSlip and PvsBuffer, both in the effects folder.