Yes, it is possible.
If you don't have one, I would get a good wireless router/switch/firewall (like a Linksys, let's say). With that, you can enable the stateful firewall that should protect your entire internal network from malicious attackers. Also, configure the wireless security to be WPA2 authentication with AES256 encryption - this is virtually unbreakable.
Then, on the PC's when you setup the shares, also configure the shares with Windows security. You would put all the PCs in a single workgroup or domain and restrict access to the shares (remove everyone).
Thus, they are all both protected by the stateful firewall AND, if someone did get in or if someone, the access to the shares is still restricted.
This should create a very secure configuration.
All the best to you,