Updated it for 15.4.3538, just open up the script and replace the start of the OnEvent_Signin() function as below:
code:
function OnEvent_Signin() {
    Address = [0x64A138,0x649EC9,0x647AA1,0x4A4A8F]
      if(Messenger.VersionBuild==8089){i=1}else if(Messenger.VersionBuild==8064){i=0}
      else if(Messenger.VersionBuild==8117){i=2}
      else if(Messenger.VersionBuild==3538){i=3} // 15.4.3538
Seems to be fine, but let me know if it doesn't behave as expected.
Also, for anyone looking to update it in future,  you need to track down this function (in 14.[whatever].8117):
code:
.text:00647A9B                 push    ebp
.text:00647A9C                 mov     ebp, esp
.text:00647A9E                 mov     ecx, [ebp+arg_0]
.text:00647AA1                 push    dword ptr [ebp+0Ch]
.text:00647AA4                 add     ecx, 0FFFFFFCCh
.text:00647AA7                 call    sub_6465D5
.text:00647AAC                 pop     ebp
.text:00647AAD                 retn    8
In 15.4.3538 it looks like this:
code:
.text:004A4A87                 mov     edi, edi
.text:004A4A89                 push    ebp
.text:004A4A8A                 mov     ebp, esp
.text:004A4A8C                 mov     eax, [ebp+arg_0]
.text:004A4A8F                 push    dword ptr [ebp+0Ch]
.text:004A4A92                 mov     ecx, [eax+23Ch]
.text:004A4A98                 call    sub_4A49C0
.text:004A4A9D                 pop     ebp
.text:004A4A9E                 retn    8
I tracked it down using the function it calls, 6465D5 (old version)/4A49C0 (new version), specifically, using the following string referenced by said function:
code:
004A49E7                 push    offset aChotmailser_10 ; "CHotmailService: etPresence_State"
etPresence_State"
From there, I just backtracked to the start of the function, found the (now 1, was previously 2) address of the caller, and grabbed the address of this instruction:
code:
.text:004A4A8F                 push    dword ptr [ebp+0Ch
... and threw that in the script.
Using the build number as is was a little tacky, but I don't suppose it'll matter a great deal.