Instant messaging on computers was a boon way back then. Here are some examples:

Hi, sis! How are things?
Fine?
Oh.

Sorry to bother, but, I kinda like need my skateboard to be fixed right now!
Sry im bsy
AW MAN!
Wait until I get my inventions done
C'MON! I HATE WAITING, AND I REALLY NEED TO GO!
Eh wot? :/

FJlnfshfwhobvds hobvshdovbhsdv vsadhvhdbvsd vsuovhsodjvbshdv sad vsovdsovjs bvhusdv svdsovbs vhbdsho vsdvsuv difuosd foasfbs o9fhusoefsaof
What were you trying to say? I think that's gibberish! Unacceptable in IM's >:(((((
Shucks!

yo man whats up (^o^)/ just gonna message with you
Hey!
chill man (-o-;)
scram
if thats the Case, man... see ya l8r

9-Volt, I'm asking your mom to take you to a movie night. Which movie?
The one with
Your wish's my command! Come on, you're gonna love it. (dont watch grave of fireflies its very saddening)
im curious about that movie you mentioned
Its a movie about a brother and baby sister who disappear forever. Oh and there's also war.
Disappear forever?! T-T

しってる?ほうけんてきなにっぽんのせんぞをそんちょうするのはよいことなので、にほんごではなすべきです。
でも、わたしたちはまだかんじでかくことをならっていません。わたしたちはひらがなしかしりません...
いつか、わたしたちはかんじでかけるようになるかもしれません。わたしたちはまだ5さいです...

Some chatting, some chatting, some chatting. Read them in their voices as you like.