It is possible to access the accelerometer directly from the MCU using the TWI (I2C) bus. However, one issue you should consider: the built-in TWR protocol stack that the MDEK1001 kit is shipped with (optionally) uses the accelerometer as a wake-up device for Tags operating in low-power mode. If you were also to try accessing the accelerometer you would probably run into conflict with the embedded protocol stack.
You can disable the Tag’s accelerometer wake-up feature by configuring the protocol stack over the USB/serial comm port or via the BLE linked Android app - however, be careful if you use the accelerometer’s interrupt pin (INT1) since it’s possible the protocol stack has an attached interrupt handler. Similarly, if you directly control the TWI you might want to consider how you use the transfer complete event (interrupt driven or polled).
If you are not planning to use the embedded TWR protocol stack, you could erase the nRF52 Flash and write your own application code using the Nordic nRF52 SDK - in which case you’ll be free to configure the accelerometer and TWI as you like.
Decawave is about to release example driver code for the TWI and the accelerometer which you could use as the starting point for your own application code development.
Hope this helps - let me know if you have further questions.