Disabling delete button in service object list fom VA03

Hi all,

i want to disable the delete and change button in attachment list of service object list (GOS) IN T CODE VA03.

I have found that it can be done by modifying the method CHECK_STATUS of class CL_GOS_SRV_ATTACHMENT_LIST,

and then calling it in t code SGOS.

i have copied this class to a Z CLASS but unable to modify the method it asks for access key.

any help is highly appreciated with example.

thanks,

pankaj gupta