The Boskone Catgirling process is repeatable because it is similar to the Professor's machine that makes Julian Friez. It's not a process; it's a device. And what a horrific one it is, too. Fortunately for 90 percent of its victims, the process usually knocks them out. Three computers and various tanks and plumbing supplies surround a tubular plexiglass "fish tank" that is large enough for two people... in the sense that a 'waved plastic skeleton counts as a person.
The victim, often bound hand and foot, is placed in the tube with the skeleton. The tube begins filling with a cocktail of specific 'wavium, modulated by the limited AIs of the computers. Over the course of 15 minutes, the victim's original body is converted to modded flesh and biosystems over the skeleton, as well as excess modding goo. The original personality arrives intact in the new nervous system. The few people who remained conscious through the process were easily broken and remolded to the Boskone whim.
As the base skeleton was a fairly typical mass-produced plastic anatomical model, the resulting catgirls are very similar in appearance, possessing "ideal" proportions and standing 169 cm tall.
The original creator of the process, Dr. Asmodeus Grey, was a discredited Supers-faction fen, trying to replicate Wolverine's "adamantium" skeleton. In typical "supervillain" fashion, he went somewhere isolated, making himself easy prey for some of the early raids. The Boskonians who intended to steal his device never expected Dr. Grey to volunteer to join them... and they definitely didn't expect him to be running their group within three months.
The main quirk for the system is that instead of ordinary supers-faction ideal models or bodybuilders, it produces catgirls. The claws and strong homeostasis possessed by the Dobbses and other "catgirled" folks are what's left of the "Wolverine" intention. Other quirks are device-dependent; quirks of the original Machine include the smell of Labatt Blue and back bacon in the air as the tube works, and the requirement for a (person-specific) carbonated beverage in the new catgirl's diet.
After the end of the war against the Boskones, many Catgirling Machines were either destroyed by the Fen or been dismantled to look for ways to reverse the process. One known counter-example is the Machine at Catgirl Industries, which has been modified to make the process as easy as possible for the ‘user’. This machine is used from time to time to allow Fen to become catgirls without the fear of technical complications.
Occasionally, rumors float around Fenspace that Dr. Grey has used the schematics for the Catgirling Machine, the Julian Friez machine, or some unholy mixture of both as the basis for something even more horrific. If there is any truth to those rumors, the results of that machine have not been seen by Fenspace... as far as any living person is aware.