heh my boy also same age as yours, almost....heehehe
i think they enjoy colouring more...so perhaps you can incorporate colouring into writing together so that its more enjoyable. Like trace a picture next to it is the alphabets so that after tracing it you go on to writing and then colour the picture?
my sons school homework is always fulla pictures to guide them into the actual writing. He also dislikes writing...always say his hands are "Suan"