Diameter 64bit Avp manipulation

this might not answer all your questions or not the best approach but it is what I used in the past

to read 64bit binary, first read it as octetstring, then use binary scan to get its value

set ccoutputoctets [DIAMETER::avp data get 414 octet source $usedserviceunit]

binary scan $ccoutputoctets W output

to format value into 64 bit binary, first, use binary format to create octetstring, then create avp from the octetstring.

set ccoutputoctets [DIAMETER::avp create 414 0 1 0 0 [binary format W 1048576]]