Hi, cramaboule,
I don't know if a 64 bit version of the dll is available, but it is possible to use the 32 bit dll with 64 bit operating systems. Simply compile your script as a x86 version and it should work.
I use this UDF and even made a huge note at the top of my script reminding me to compile it as x86 for it to work. I have stumbled upon this problem with a couple other .dlls in the past.
Another note, I separated my scripts into a main script and one that just does the printing, so I don't have to worry about compiling my main script as 32 bit. My main script does all the Gui and text stuff and then I send the data off to a "PrintPage.exe" that is 32 bit. Basically, I just write the data to an .ini file and have the printing executable read the data.