I'm pretty sure it would fit without any problem. Leatherman.com sells them for $5 and the three pocket new Wave sheath for $6.
[Added] The product info for the Standard Nylon Belt Sheath says it should fit the following models:
PST PST II Sideclip Flair Original Wave
Pulse Crunch Kick Fuse Blast
Even with $5 shipping it's a decent deal. BTW, many pistol magazine sheaths will fit the LMWave and other multitools and will be less flashy. If you have any lying around the house, they are worth a try.
The original LMWave came in a semi-rigid nylon holster (I think made by Bianchi with their exclusive Accumold process) which fit like a glove and held it's shape without being too "stiff". This was discontinued in favor of a floppy "envelope" nylon holster :barf: . With the new tools, we have elastic sides like the sheaths from the juice line. I haven't tried the newer Wave sheath but I can't imagine elastic sides being better than the original semi-rigid sheath.