Hi Allen,
Yes, you can check if a table is opened excl without any error message.

*Prior to opening the table, disable the normal error handling...
ON ERROR ?""
*Attempt to open the table...
SELECT 0
USE mytable EXCL
IF EMPTY(ALIAS())
WAIT WINDOW "Cannot get exclusive use!"
ELSE
*You have opened the table exclusive!
ENDIF
*Be sure to restore the error handler!
ON ERROR

Hope that helps,
Julian