Here's what my
plant propagation textbook says. Use the tips of vigorous pencil-size shoots in late
spring and placed under mist. Wounding (use a knife to scrape a strip of bark off the stem) and relatively strong applications of rooting hormone are helpful. Stick into a sand-peat mix or use a 1:1 mixture of peat and perlite. It's often difficult to overwinter rooted maple cuttings. Try to induce new growth shortly after rooting, by using lighting and fertlizer.
Also, you can try taking hardwood cuttings in midwinter and root in a
greenhouse after wounding and using rooting hormone
