A basic script to set, check, del an infoline for a channel. This is channel specific, I didn't add a global option. There was a reason for that :)

Commands are:
!infoline add text to add for infoline
to add a new infoline, or replace an old one.
NOTE: text for infoline is restricted to 120 characters. Exceeding this limit will cut the text off.

!infoline del
to remove set infoline.

!infoline show
to show current infoline.

!greet on|off
to enable|disable the greet setting for the channel.

# $Id: infoline.tcl,v1 25/01/2013 02:29:42am GMT +12 (NZST) istok@IRCSpeed.org Exp $
# Set global trigger here
set triga "!"

# Set global flags allowed to use infoline and greet commands.
set globflags o

# Set channel flags allowed to use infoline command.
set chanflags vo

# Set channel flags allowed to use the greet command.
set chanflags2 m

# ----- NOTHING ELSE TO SET! -----
proc getTrigger { } {
  global triga
  return $triga
}

bind pub - ${triga}infoline info:line

proc info:line {nick uhost hand chan arg} {

  global globflags chanflags
  if {![matchattr [nick2hand $nick] $globflags|$chanflags $chan]} {return}

  if {([lindex [split $arg] 0] == "") && (![regexp c [getchanmode $chan]])} {putquick "PRIVMSG $chan :\037ERROR\037: Incorrect Parameters. \037SYNTAX\037: [getTrigger]infoline add whatever text you want - [getTrigger]infoline del - [getTrigger]infoline show"; return}

  if {([lindex [split $arg] 0] == "") && ([regexp c [getchanmode $chan]])} {putquick "PRIVMSG $chan :ERROR: Incorrect Parameters. SYNTAX: [getTrigger]infoline add whatever text you want - [getTrigger]infoline del - [getTrigger]infoline show"; return}

  if {[lindex [split $arg] 0] == "add"} {

    set infotext [join [lrange [split $arg] 1 end]]

    setchaninfo "[nick2hand $nick]" "$chan" "$infotext"

    if {![regexp c [getchanmode $chan]] && ![channel get $chan greet]} {putquick "PRIVMSG $chan :InfoLine for \002$nick\002 now set to \002$infotext\002"; channel set $chan +greet ; return}

    if {[regexp c [getchanmode $chan]] && ![channel get $chan greet]} {putquick "PRIVMSG $chan :InfoLine for $nick now set to $infotext"; channel set $chan +greet ; return}

    if {![regexp c [getchanmode $chan]]} {putquick "PRIVMSG $chan :InfoLine for \002$nick\002 now set to \002$infotext\002"; return}

    if {[regexp c [getchanmode $chan]]} {putquick "PRIVMSG $chan :InfoLine for $nick now set to $infotext"; return}

  }

  if {[lindex [split $arg] 0] == "del"} {

    if {[getchaninfo [nick2hand $nick] $chan] == ""} {putquick "PRIVMSG $chan :You currently have no infoline set for $chan"; return}

    setchaninfo "[nick2hand $nick]" "$chan" "none"

    if {![regexp c [getchanmode $chan]]} {putquick "PRIVMSG $chan :InfoLine for \002$nick\002 has now been \002removed\002."; return}

    if {[regexp c [getchanmode $chan]]} {putquick "PRIVMSG $chan :InfoLine for $nick has now been removed."; return}

  }

  if {[lindex [split $arg] 0] == "show"} {

    set showtxt [getchaninfo [nick2hand $nick] $chan]

    if {$showtxt == ""} {putquick "PRIVMSG $chan :You currently have no infoline set for $chan"; return}

    if {![regexp c [getchanmode $chan]]} {putquick "PRIVMSG $chan :InfoLine for \002$nick\002 currently set to: \002$showtxt\002"; return}

    if {[regexp c [getchanmode $chan]]} {putquick "PRIVMSG $chan :InfoLine for $nick currently set to: $showtxt"; return}

  }

}

bind pub - ${triga}greet greet:pub

proc greet:pub {nick uhost hand chan arg} {

  global globflags chanflags2
  if {[matchattr [nick2hand $nick] $globflags|$chanflags2 $chan]} {

    if {[lindex [split $arg] 0] == ""} {putquick "PRIVMSG $chan :\037ERROR\037: Incorrect Parameters. \037SYNTAX\037: [getTrigger]greet on|off"; return}

    if {[lindex [split $arg] 0] == "on"} {

      if {[channel get $chan greet]} {putquick "PRIVMSG $chan :\037ERROR\037: This setting is already enabled."; return}

      channel set $chan +greet

      puthelp "PRIVMSG $chan :Enabled Greets for $chan"

    }

    if {[lindex [split $arg] 0] == "off"} {

      if {![channel get $chan greet]} {putquick "PRIVMSG $chan :\037ERROR\037: This setting is already disabled."; return}

      channel set $chan -greet

      puthelp "PRIVMSG $chan :Disabled Greets for $chan"

    }

  }

}

putlog "InfoLine Module Loaded! - istok@IRCSpeed.org"