(Note: I have not fully tested this method.)
You should be able to get a local install working by editing your hosts file. (ex. c:\windows\system32\drivers\etc\hosts)

In the hosts file put something like this at the end:
127.0.0.1 site1.local
127.0.0.1 site2.local

(Or whatever URLs you would like to type in your address bar in place of site1.local/site2.local.)

Also, make sure your multisites config files are named accordingly. (ex. site1.local_config.php)