Can someone explain cls-*.dlls and how to use them?

[describe19]

Hello I've been reading a lot around this forum and I am making a repack with srep+lolz.

I downloaded lolz from krinkels.org and I have a packcmd specified in arc.ini, however I do not need an unpackcmd as somehow the cls-lolz.dll does it automatically...I need to move the cls-lolz stuff it away from arc.exe during packing though as it seems to interfere.

I tried using ProFrager's cls-srep files from krinkels.org but when I unpack my file compressed with srep+lolz I get a crc check error, this doesn't happen when I use cls-lolz and normal srep64.exe -d -s -- <stdin> <stdout> in arc.ini.

My questions are:
How do cls-*.dlls work with arc.exe and unarc.exe - what happens? I have tried searching but haven't been able to find much about cls plugins.
How can I use other cls dlls like cls-srep.dll?
Is there a way I can use cls dlls to unpack without an arc.ini at all?