Tekkit server Command Question (lava bucket placement)

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So I got my server running nicely with some friends on it, but I cant seem to find (its a survival server btw) the command to put in my permissions file (using groupmanager) for them to be able to use lava buckets. They can pick it up, just not put it down somewhere.

I truelly looked through a load of commands, but couldnt find the correct one. Anyone know the command?

And another small question, my OS is in Dutch, and my server also outputs dutch.. My friends are english, is there a way to change the server to english? I couldnt find it in server.properties. Any ideas? Thanks