pretty sure UltimateZip on the PC (yes, boo hiss) can support multi-volume archives, and, it supports LHA files, too. UltimateZip is freeware (
http://www.ultimatezip.com) but PC only, unfortunately, but, if you can get the files to a PC and then make multi-zip archives, you could then download those to an Amiga elsewhere. .. .
kevin orme
amiga university
www.amigau.com