You can write ISL script to show the message then invoke function 458767 (On Demand Customer Receipt). Assign that script to your key.
Here is script example:
[pre][tt]var myPrintCheck:n2 = 1
event inq: myPrintCheck
var print_check : key
var kKeyPressed : Key
var sTmpData : A10
InputKey kKeypressed, sTmpData, "Have you asked customer about rewards?"
if (kKeypressed = @KEY_ENTER)
print_check = key(1, 458767)
LoadKyBdMacro print_check, @Key_Enter
endif
endevent[/tt][/pre]
You'd need to create interface for that script, put the script file into proper CAL folders, then use Category SIM/PMS Inquire in the button definition