perl 
-wlne"printf qq[\t'%s'\n], join qq['+\n\t'], m[(.{1,34}(?: |$)|.{34})]g" 
junk.txt
        'Here is one big long string which '+
        'needs to have some formatting done '+
        'to it before I can use it for '+
        'input in a separate program.'
        'I would like it to be formatted '+
        'exactly as follows (except for the '+
        'exact line length)'

##</code><code>##

#! perl -slw
use strict;

for my $n ( 4 , 34, 70 ) {
    print "\n$n";
    my $pos = tell DATA;
    while( <DATA> ) {
        chomp;
        printf "\t'%s'\n", join "'+\n\t'", m[(.{1,$n}(?: |$)|.{$n})]g;
    }
    seek DATA, $pos, 0;
}
__DATA__
Here is one big long string which needs to have some formatting done to it before I can use it for input in a separate program.
I would like it to be formatted exactly as follows (except for the exact line length)

##</code><code>##

P:\test>junk

4
        'Here '+
        'is '+
        'one '+
        'big '+
        'long '+
        'stri'+
        'ng '+
        'whic'+
        'h '+
        'need'+
        's to '+
        'have '+
        'some '+
        'form'+
        'atti'+
        'ng '+
        'done '+
        'to '+
        'it '+
        'befo'+
        're I '+
        'can '+
        'use '+
        'it '+
        'for '+
        'inpu'+
        't in '+
        'a '+
        'sepa'+
        'rate '+
        'prog'+
        'ram.'
        'I '+
        'woul'+
        'd '+
        'like '+
        'it '+
        'to '+
        'be '+
        'form'+
        'atte'+
        'd '+
        'exac'+
        'tly '+
        'as '+
        'foll'+
        'ows '+
        '(exc'+
        'ept '+
        'for '+
        'the '+
        'exac'+
        't '+
        'line '+
        'leng'+
        'th)'

34
        'Here is one big long string which '+
        'needs to have some formatting done '+
        'to it before I can use it for '+
        'input in a separate program.'
        'I would like it to be formatted '+
        'exactly as follows (except for the '+
        'exact line length)'

70
        'Here is one big long string which needs to have some formatting done '+
        'to it before I can use it for input in a separate program.'
        'I would like it to be formatted exactly as follows (except for the '+
        'exact line length)'