This requires that the user saying !link or !delink is on the User List as level "Linker".
It's pretty self-explanatory, and the format of the !link command is a comment on the first 'on text' script.

Note: This script CAN and WILL get spammy if used to link large channels together and I'm not liable for anyone using this getting network banned for spamming. It is a script meant for smaller rooms with both owners consent.

It can link at most 2 channels on 2 different networks, though can be expanded fairly easily if one understands the script.

Author: Rolo @ #mIRC on Purplesurge

#link on
on *:connect:set % [ $+ [ $network ] $+ [ .cid ] ] $cid

on Linker:text:!link & &:#: {
  ; !link network channel
  if ($$2 == $network) {
    unset %Network*
    set %Chan1 $chan
    if ($me !ison $$3) join $$3
    set %Chan2 $$3
  }
  else {
    var %networkcheck 1
    :netcheck
    if ($scon(%networkcheck).network == $$2) {
      set %Network1 $network
      set %Network2 $$2
    }
    else {
      inc %networkcheck
      goto netcheck
    }
    set %Chan1 $chan
    if ($me !ison $$3) scid % [ $+ [ $$2 ] $+ [ .cid ] ] join $$3
    set %Chan2 $$3
  }
}

on Linker:text:!delink:#: unset %Chan* %Network*

on *:text:*:#:{
  if (!%Network1) {
    if ($chan == %Chan1) .msg %Chan2 $chan $+(<,$nick,>) $remove($1-,$chr(36),$chr(37))
    if ($chan == %Chan2) .msg %Chan1 $chan $+(<,$nick,>) $remove($1-,$chr(36),$chr(37))
  }
  else {
    if ($chan == %Chan1) && ($network != %Network2) scid % [ $+ [ %Network2 ] $+ [ .cid ] ] .msg %Chan2 $chan $+(<,$nick,>) $remove($1-,$chr(36),$chr(37))
    elseif ($chan == %Chan2) && ($network != %Network1) scid % [ $+ [ %Network1 ] $+ [ .cid ] ] .msg %Chan1 $chan $+(<,$nick,>) $remove($1-,$chr(36),$chr(37))
  }
}

on *:join:#:{
  if (!%Network1) {
    if ($chan == %Chan1) .msg %Chan2 $chan * $nick has joined ( $+ $remove($address($nick,0),*!) $+ )
    if ($chan == %Chan2) .msg %Chan1 $chan * $nick has joined ( $+ $remove($address($nick,0),*!) $+ )
  }
  else {
    if ($chan == %Chan1) && ($network != %Network2) scid % [ $+ [ %Network2 ] $+ [ .cid ] ] .msg %Chan2 $chan * $nick has joined ( $+ $remove($address($nick,0),*!) $+ )
    elseif ($chan == %Chan2) && ($network != %Network1) scid % [ $+ [ %Network1 ] $+ [ .cid ] ] .msg %Chan1 $chan * $nick has joined ( $+ $remove($address($nick,0),*!) $+ )
  }
}

on *:part:#:{
  if (!%Network1) {
    if ($chan == %Chan1) .msg %Chan2 $chan * $nick has parted ( $+ $remove($address($nick,0),*!) $+ )
    if ($chan == %Chan2) .msg %Chan1 $chan * $nick has parted ( $+ $remove($address($nick,0),*!) $+ )
  }
  else {
    if ($chan == %Chan1) && ($network != %Network2) scid % [ $+ [ %Network2 ] $+ [ .cid ] ] .msg %Chan2 $chan * $nick has parted ( $+ $remove($address($nick,0),*!) $+ )
    elseif ($chan == %Chan2) && ($network != %Network1) scid % [ $+ [ %Network1 ] $+ [ .cid ] ] .msg %Chan1 $chan * $nick has parted ( $+ $remove($address($nick,0),*!) $+ )
  }
}

on *:rawmode:#:{
  if (!%Network1) {
    if ($chan == %Chan1) .msg %Chan2 $chan * $nick sets mode: $1-
    if ($chan == %Chan2) .msg %Chan1 $chan * $nick sets mode: $1-
  }
  else {
    if ($chan == %Chan1) && ($network != %Network2) scid % [ $+ [ %Network2 ] $+ [ .cid ] ] .msg %Chan2 $chan * $nick sets mode: $1-
    elseif ($chan == %Chan2) && ($network != %Network1) scid % [ $+ [ %Network1 ] $+ [ .cid ] ] .msg %Chan1 $chan * $nick sets mode: $1-
  }
}

on *:action:*:#:{
  if (!%Network1) {
    if ($chan == %Chan1) .msg %Chan2 $chan 6* $nick $remove($1-,$chr(36),$chr(37))
    if ($chan == %Chan2) .msg %Chan1 $chan 6* $nick $remove($1-,$chr(36),$chr(37))
  }
  else {
    if ($chan == %Chan1) && ($network != %Network2) scid % [ $+ [ %Network2 ] $+ [ .cid ] ] .msg %Chan2 $chan 6* $nick $remove($1-,$chr(36),$chr(37))
    elseif ($chan == %Chan2) && ($network != %Network1) scid % [ $+ [ %Network1 ] $+ [ .cid ] ] .msg %Chan1 $chan 6* $nick $remove($1-,$chr(36),$chr(37))
  }
}
#link end