tcpdump/snort to capture chat sessions

[R J]

I am trying to use tcpdump (or snort, but they are both behaving the same 
in this case) to capture all the lines or contents of an msn 
chat session, the actual conversation.  I am getting partial output; i.e, 
I'll only get half of a sentence, and I don't see the rest of the lines. 
And ofcourse, alot of it seems to be hex or obfuscated html?

What switches do I need to capture the entire lines of text?

I am using these options with snort:

snort -i hme1 -v -K None -X

That's sending output to stdout, which is fine with me.

Thanks for any pointers/suggestions/recommendations.

Robert