This will allow you to long press the search button to ignore a phone call and it will prompt you to automatically send that person a text saying you are busy or not.
New - Type: Phone Ringing - OK - Event - Phone - Phone Ringing - Priority: Highest - Done - New Task - Ok
"+" - Variable - Variable Set - %PHONERING to 1 - Done
"+" - Tasker - Wait - 30 Seconds - Done
"+" - Variable - Variable Set - %PHONERING to 0 - Done - Done
Tasks - New Task - Type: Autotext
"+" - Phone - Send SMS - Number: %CNUM - Message: Sorry, I am busy, I'll call you back later. - Done
"+" - Alert - Flash - Text: "Msg Sent" - Done
Tasks - New Task - Type: Stop
"+" - Tasker - Stop - Done
New - Type: Ignore Call - Ok - State - Variable Value - %PHONERING matches 1 - Done - New Task - Ok
"+" - Phone - End Call - Done
"+" - Alert - Popup Task Names - Task (first one) - Press the magnifying glass - Select: Autotext - Task (Second One) - Select: Stop - Done - Done
Add another context (By clicking Variable Value in the Ignore Call profile) - Event - Hardware - Button: Long Search - Priority: Highest - Done - Apply
Special Thanks to Mr. H. Smith for helping me test this.
If you need any help send an email to peterobri at gmail dot com