1. Go to your Mac OSX drive, open it up. Open Library folder, then Receipts folder, find
Install LimeWire.pkg & trash it. Example of where to find it here:
Receipts folder sample image
2. Find LW 4.18 here:
Older Versions for LimeWire & download the version for OSX 10.4

Install this version. With the newer version Receipt you would not be able to install the older LW so it needs to be removed first.
(b) I gave the direct link above, but normally you will find the
'Older Versions' link on the right-side of the normal LW download page. It's on the left-side of the page for Pro users' personal download page.
.