This way... so you don;t have to restart httpd every time you update the rules:
RewriteMap filt-bloc txt:/this/is/someplace/filter-ip-block.txt
RewriteCond ${filt-bloc:%{REMOTE_ADDR}} =1
RewriteRule . - [F]
But then, you will have to add the IPs to the text file individually like this:
12.34.56.64 1
12.34.56.65 1
12.34.56.66 1
12.34.56.67 1
12.34.56.68 1
12.34.56.69 1
...
12.34.56.95 1
But its very flexible and handy.