<input type=checkbox value=aaa onclick="if(this.checked)document.all.meizz.value=this.value">1<br>
<input type=checkbox value=bbb onclick="if(this.checked)document.all.meizz.value=this.value">2<br>
<input type=checkbox value=ccc onclick="if(this.checked)document.all.meizz.value=this.value">3<br>
<input type=checkbox value=ddd onclick="if(this.checked)document.all.meizz.value=this.value">4<br>
<input type=checkbox value=eee onclick="if(this.checked)document.all.meizz.value=this.value">5<br>
<input type=checkbox value=fff onclick="if(this.checked)document.all.meizz.value=this.value">6<br>
<input type=checkbox value=ggg onclick="if(this.checked)document.all.meizz.value=this.value">7<br>
<input type=checkbox value=hhh onclick="if(this.checked)document.all.meizz.value=this.value">8<br><input name=meizz>