It is difficult enough to not be worth it in most cases to add new input styles to Harlowe. It is possible, but it requires some hacking and abuse. You're far better off upgrading to Harlowe 2 and using a for loop and links if at all possible. You really shouldn't be using an old version anyway, unless you have no choice, for example because the game is basically finished or you can't get it running in v2.x.