Hello Keni,
You can download the example software for the CC2541/43/44/45. In there you can find examples without BLE. Using the current consumption document as you guide, you will be able to test the MCU under different conditions. The swrc257.zip contains the example.
I don't know how you are going to reduce the the internal clock from 32MHz to 1MHz, but if you find a way, the current consumption document should still be useful.
Another option is to load one of the sample projects and in the xxxx_Main.c, comment out osal_start_system(); // No Return from here. This will at least load everything and allow you to play with the clock using all the OSAL and HAL functions.
Thanks,