Payload field value in container for alert

Hi All,

I am configuring Alerts for my client.I have to insert a value of one of the field from payload in the alert long message.

I have gone through SDN to search for any blogs.

1) I dont want to use BPm

2) Other option of using RFC lookup in mapping is not feasible.

Does any one else has any other idea about implementing the same.I could see some System Fields like XPATH_GET_VALUE in the alert category.But ,how can we use it?

Thanks

Nidhi