This was done for me some time ago in the help forum and i thought it was time to submit it as tribute.. i cant find the url so am unable to find who helped me.
If the creator can come forward with the ORIGINAL url i will gladly accredit this to you.

this is a counter that checks if you have typed too many characters in a sentance. you set the variable (400) to the server default character allowance for a line and if you go over it on a sentance, it will not post it. as per this quote below

• Timer 1 activated
  Line size is too long - 15 characters over the allowed limit.
  • Timer 1 halted

then you just delete appropriate characters on your typing line and hit enter. then it will post without the server cutting it off.

loads into a new clean remotes and is good for mirc 6.3 and up.

 on *:input:#:if ($len($1-) > 400) { timer 1 1 echo 4 -a Line size is too long - $calc($len($1-)-400) characters over the allowed limit. | editbox -a $1- | halt }