Halve the squash lengthwise and scoop out the seeds. Put the squash, cut-side up, in a large microwave-safe bowl and drizzle with 1 tablespoon olive oil and 1 tablespoon water. Season with salt and pepper. Cover tightly with and microwave until tender, about 20 minutes. Scoop out the flesh into a colander (use a towel to hold the squash) and shred with 2 forks.
Meanwhile, heat a grill pan over medium heat. Grill the sausages, turning, until cooked through, about 20 minutes.