I presume you're talking about OpenZaurus (OZ)?
The package manager is a bit broken so you have to use ipkg from the command line:
ipkg install somepackage.ipk # will install to root (flash ROM)
ipkg install -d sd somepackage.ipk # will install to SD card
ipkg install -d cf somepackage.ipk # will install to CF card
You can also remove the default package manager and install aqpkg instead; there's a thread about this in the OpenZaurus part of the forum.
Syncing - you need to use the old Sharp software (which came with the 2.xx sl5500 ROMs); there are other things you can do but I don't sync so that's as much as I know.
We're trying to pull together documentation for OZ (
https://www.oesf.org/forums/index.php?showtopic=7997).
Si