It worked!

 

I got the eucalyptus leaves from Hardy's florist, and set to work.  The scarf had been soaking in a vinegar solution to mordant it in advance of starting the printing process.  I laid the felted scarf out on my longest studio bench, placed a line of leaves along it, folded it in half lengthwise so that the leaves were covered, and rolled it in a bundle around some plastic pipe.  I secured the rolled bundle with elastic bands and jute twine, then steamed it in (a non-food use) electric steamer for 1 hour.  I removed it, and left it to cool over night.  I unwrapped it today, and you can see the amazing colour that the eucalyptus gives on the wool.