hackaBLE does not ship with a bootloader, but it is supported in Arduino. Please visit here for details (but select hackaBLE in the board's menu).
Here's a blog article which will help you create a BLE custom characteristic and program it to hackaBLE using Arduino IDE.
The detailed hackaBLE programming guide comming soon.
Using Web Bluetooth
You can connect directly to hackaBLE using Web Bluetooth. For this to work, your browser must support Web Bluetooth. To check list of available browsers, visit this link. On Google Chrome, you should have enabled experimental web features by visiting the url :
Try it here !
This demo shows temperature and humidity data received over BLE from sensor attached to hackaBLE. You can access the Firmware at this link.