What is "Cresol Soap"?
According to an 1894 tract with the title Merck's Market Report and Pharmaceutical Journal: An Independent Monthly Magazine Devoted to the Professional and Commercial Interests of the Druggist, Volume 3, "cresol soap" was also called "crelium" or "crelium soap".
The google n-gram viewer suggests that "cresol soap" is a historical term, whose usage began in the 1890s, peaked dramatically during World War I and its immediate aftermath, and declined substantially afterwards.
A 1915 British medical report argues for using cresol soap as a vermin control agent in troop populations.  It gives a recipe as:


10 gallons of water
1.5 pounds of soft soap
Jeyes' fluid 1.5 ounces


This raises the question of what "Jeyes' fluid" is. Amazingly, Jeyes' Fluid is apparently still a commercial product, and contains a mixture of 4-chloro-m-cresol, isopropanol, terpineol, and "tar acids".  
"Cresol soaps" are apparently still an item of commerce somewhere in the world, as a 2011 applications report form an analytical equipment vendor illustrates the analysis of a "cresol soap" sample, although a specific source is sadly not mentioned.  The primary detected constituents were m-cresol and p-cresol.


I suspect there are many other recipes that involve mixing soap, water, and crude cresol preparations of various kinds.  In the era of cresol soap's invention and popularity, coal was far more ubiquitous than now, and the cresol sources were probably crude fractions of distilled coal tar that were enriched in various isomers of cresol.  In those days awareness of potential toxicity from cresols was also not as developed as now.  The "tar acids" in Jeyes' fluid probably include a variety of cresol isomers.