Set to run iMacros Randomly

This is my code :

TAG POS=1 TYPE=INPUT:CHECKBOX ATTR=ID:check1 CONTENT=YES       
TAG POS=1 TYPE=INPUT:CHECKBOX ATTR=ID:check8 CONTENT=YES       
TAG POS=1 TYPE=INPUT:CHECKBOX ATTR=ID:check14 CONTENT=YES      
TAG POS=1 TYPE=INPUT:CHECKBOX ATTR=ID:check19 CONTENT=YES      
TAG POS=1 TYPE=SELECT ATTR=ID:t_score CONTENT=%0.75                      
TAG POS=1 TYPE=BUTTON ATTR=TXT:Submit<SP>Number  

I want to set line 1 to run Randomly,for example it differs from check1 to check6
And in line 2 it differs from check7 to check12
And in line 3 it differs from check13 to check17
And in line 4 it differs from check18 to check21
And in line 5 Number differs from 0.75 to 1
thanks...