Alt logger?

I believe the OP is a factions player and just wants to log on alts.

Darkbot lets you do this and it has just recently been updated. Darkbot isn't posted here though so you'll have to use google to find it.

Is it in a client or is it just a client without hacks that allows you to log alts on?

No, it's a separate program you have to compile yourself. If you don't feel like you can do that, there's some other bots coming out like Apocalypse (made by Klinots). He's not on these forums though so you'll have to look elsewhere.

Use a server spammer that logs alts, but make alts spam a command, rather than text in chat.

Use DarkBoat. Google search it!