join qq{\n}, 
    qq< #some code          >,
    qq< #more code {        >,
    qq<    #indented code   >,
    qq< };                  >,
     ;

##</code><code>##

$saved_line    = get_line(?);   # get source line number somehow
s{whatever;}
 {whatever;
     inserted code;
     and another line of the same;
 #line $saved_line
 }g