Generally l unzipped the .vroidcostumitem file of newly created Sock style, then opened a file with ".transferable" extension inside it. Then inside file if it contains a string:
MeshOverrideFlag.N00.Socks
l replaced it to (using hexadecimal editor):
MeshOverrideFlag.N00.Shoes
And replaced ".transferable" file.
And it did the trick surprisingly enough. The other thing though:
https://booth.pm/en/items/4983661
Is more complicated to do. Basically it requires changing one string from Shoe to Top, and that has another string size so numerous (6 or so) size descripting values' replacement is required, or else Vroid Stuidio will say it's a bad item.
Don't be afraid, it's absolutely impossible to hide an executable inside a hacked item that will record your passwords or something.