Will be testing it in production later today or maybe tomorrow/thurs (custom lock screens aren't exactly high priority!) so will report back if it all goes TITSUP. Aye, it doesnt appear to be that well documented, I found an obscure blog post about it from before Windows 7 even came out and did some digging, I found a few posts, even one on here but all of them made suggestions that it didnt work but so far, on a test VM its working an absolute treat.