You may have more luck looking for free analysers that use the raw squid logs rather than the WELF logs. Is there a particular reason for a WELF analyser over the squid logs?
Try SAWMILL, runs on all kinds of OSs - windows, mac, linux. It has a pile of other log formats (My config folder shows 247). It is really a great product.
I use this one product to analyze our Merak Mail server stats, our Webstar Web and FTP stats, and the Astaro stats.