Of course you can use e.g. $deltok(%itemdata,1-3,32) instead of $gettok(%itemdata,4-,32).
The negative N was to illustrate that there are multiple ways to get some tokens... And there is no token limit but a length limit: prior to mIRC 6.32 it's been aprox. 940 chars (name of hash table + name of item + data of item), mIRC 6.32 extended it to aprox. 4140 chars.