Modifying a bluetooth dongle

My bluetooth dongle has a 24c32 serial eeprom before the connection to usb, is there any way to interface it with a uC from there ?

Yes, with a sniffer and some analyzing software is it simple. I2C is a common protocol and SDA and SCL pins are known. Cheap sniffers can be bought. I have built a sniffer consisting of only two components, a 80c51 and a cap for Vcc decoupling. With size 3*3 mm do it fit inside most things. It is clocked at 100 MHz as I2C data rate can be up to 400 kHz, Do not know if it is optimal solution, it was what I had available useable as sniffer. MCU's with existing I2C interface is as far as I know, less suited for sniffing.

so the data pins of the USB, D+ and D- , may be the SCL and SDA ?

I doubt that, nether protocol or speed is the same.
It is possible that I2C protocol also addresses a special USB driver but a simple Bluetooth dongle have USB part integrated in same chip as the Bluetooth chip.

oh, so i have to sniff through the SCL and SDA of the serial eeprom, isnt it ?

Maybe. A bit curious, why do you want to do this? If it is a common Bluetooth chip, information in the eeprom is probably just boring setup instructions for the Bluetooth chip and this information is much simpler to read of line even if you need to unsolder it.