Something

alias code { 
  msg $chan § $replacex($1- ,a,K@,b,_:,c,O3",d,IO7',e,H9`,f,C4V,g,N<,h,|[/,i,":|,j,JU\,k,973>,l,9-,m,X2,n,MI=,o,PF_,p,KV],q,ET!,r,NB*,s,LI^,t,ND&,u,FG%,v,$chr(35),w,JQ[,x,GV$,y,XT°,z,+LD,1,IVH,2,ElG,3,DvG,4,JxC,5,LHR,6,CJiE,7,RvETN,8,NOQS,9,SNBI,.,$chr(40),$chr(44),$chr(41),$chr(39),$chr(47),0,NCY,?,¯)
}

alias decode {
  echo -a 5*** Decode - $+ $nick $+ - $replacex($1- ,SNBI,9,NOQS,8,RvETN,7,CJiE,6,LHR,5,JxC,4,DvG,3,ElG,2,IVH,1,+LD,z,XT°,y,GV$,x,JQ[,w,$chr(35),v,FG%,u,ND&,t,LI^,s,NB*,r,ET!,q,KV],p,PF_,o,MI=,n,X2,m,9-,l,973>,k,JU\,j,":|,i,|[/,h,N<,g,C4V,f,H9`,e,IO7',d,O3",c,_:,b,K@,a,$chr(40),.,$chr(44),$chr(41),$chr(47),$chr(39),NCY,0,¯,?)
}

on *:TEXT:§*:#:{  
  decode $2-
}