What is specifically illegal in the United States is transacting in spermaceti, the oil from the nasal cavity of sperm whales. This is the specific oil that the old masters used along with beeswax and other more dubious substances like beef suet to finish their pipes. The late French pipe carver, Philippe Bargiel, the same one who insisted on applying spermaceti to meerschaum, found jojoba oil to be chemically identical to spermaceti. Before he died, Fred Bass and I briefly discussed the use of jojoba esters instead of oil. White filtered (not chemically bleached) beeswax, jojoba oil and esters are all available on the Internet. I have experimented with beeswax melted with jojoba oil but have not tried esters.
The address below is for a set of pictures of a 19th century Ulmer variant and the rapid coloration induced by a beeswax-jojoba paste. The pipe has to be around 120 years old. The stummel was therefore filled with tobacco combustion byproducts. Apparently, the previous owner allowed the original wax coating to wear off so when I refinished it, the resulting coloration was drastic and swift.
https://www.flickr.com/photos/41273109@N02/16067109323/in/album-72157632472761650/