Our IRC-Channel #vzekc at hackint is usable with every IRC client.
using TLS, respectively:
Recommended clients for Windows are e.g. HydraIRC or classic mIRC.
On Linux weechat, irssi, HexChat, xchat, ... can be used.
Für OSX there is e.g. LimeChat.
Alternatively you can use the web client.
Ideally, you simply keep the client running in the background, so others can respond. Not everyone keeps staring on the screen and waits for something to happen