It should be possible - assuming your field is called mynum, insert a
standard merge field and use Alt-F9 to reveal the code. You should see
something like

{ MERGEFIELD mynum }

Add a numeric format switch as follows:

{ MERGEFIELD mynum \#"0'-'000" }

Assuming the CC020-0 part is constant just put it outside the Mergefield,
e.g.

CC020-0{ MERGEFIELD mynum \#"0'-'000" }

Peter Jamieson