Forcing Lua on Windows to use a standalone folder

[mchalkley@...]

I've got to add a feature to a Lua program I wrote several years ago,
but it was 5.1 and uses sigar to check system stuff (Disk, memory, &
CPU usage, etc.) and sigar is broken on 5.2.

My machine now has a 5.2 LuaRocks installation, and I can't figure out
a way to get lua to ignore all the system environment variables from
within a command prompt window.

For example, if I run the lua script on a target machine that doesn't
have lua installed, it runs fine, but if I run it on my machine, I get
all kinds of module not found warnings, etc.  If I resolve those, lua
barks about lua52.dll being missing, even though it's running 5.1.

Any ideas on how I can make a command prompt window ignore everything
but what's in the folder I'm running from?  Setting %PATH% to just ;
doesn't help - lua continues to look in the LuaRocks\Systree... folder
for lfs, etc.