Thanks Rick. Hope this is my last question here 
....I have checked few threads in SCN about setting virtual attributes in BO and use it in workflow start condition? Is it possible to set virtual attribue in USER exit and check the value in work flow start condition? Or we need to have data base field? ...if this is not possible I would rather go with custom event as i don't want to extend standard table for this field?
Or with the combination of check function module at start condition and EXPORTing a value in the userexit then IMPORTing it in the function module...
I wanted to use the best available solution without disutrbing standard sap functionality