http://bugs.winehq.org/show_bug.cgi?id=58550
--- Comment #2 from Björn Kautler Bjoern@Kautler.net --- Thanks for the quick reply and sorry for the duplicate, didn't identify that one. :-(
winepath will do the PATH translation for you (no need of a .bat for that)
Of the executable, yes, but not for the arguments. The argument to the called process is the absolute path of the file to sign and that needs to be translated using `winepath` in the BAT file or JSign complains that it cannot find the Windows-style path.
As a work-around I now indeed again do provision a Windows JRE and use that instead of the host executable. With that it works like a charm.