How can I release the Win-L key combination to the underlying program?

Question

I'm a Mac user (boo, hiss, I know) who's occasionally working on a Windows 8.1 partition on his Macbook. I've used AutoHotKey to remap several keys, and make my life easier by sharing the same general keyboard-shortcuts between OS X and Windows.

Most crucially, I've swapped RCtrl and RWin, because the primary modifier key on OS X (Command) is right next to the space-bar, accessible by the thumb; instead of being off in the corner, something you have to stretch for with your pinkie-finger, as the primary modifier key is on Windows (Ctrl). (I much prefer "Thumb-W" to close a window, for instance, to "Contort-Hand-and-Attempt-Pinkie-W".)

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The problem I'm running into, is one of my most-used keyboard shortcuts: command-L on OS X, in Chrome or Safari. This focuses the URL bar. Unfortunately, on Windows, win-L is apparently perma-mapped by default to lock the screen, and AutoHotKey makes no attempt to remap that. My muscle memory has me accidentally locking my screen every couple minutes, and it's driving me nuts.

I've dug out a registry-hack that completely disables the "workstation lock" feature of Windows, and that's half-solved the problem for me; but now, although it no longer locks my machine, neither can I figure out how to remap it to do anything else.

Here's the relevant part of my AutoHotKey script; can somebody tell me how to modify this to actually work (with "DisableLockWorkstation" enabled) on Windows 8.1?

#l::^l
#r::^r

RCtrl::RWin
RWin::RCtrl
LCtrl::LWin
LWin::LCtrl

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Edit 1: I've tried some more experimenting, and discovered that AutoHotKey straight-up refuses to even capture win-L. Out of the following, the first two cause windows, but the latter has no effect:

!l::MsgBox, "You pressed Alt-L"
^l::MsgBox, "You pressed Ctrl-L"
#l::MsgBox, "You pressed Win-L"