As from January 1st 2013:

Step 1: Software setup (using EuroScope Starters Package)
Step 2: Logging 10 hours as observer
Step 3: ATSimTest Student 1 rating theory test
Step 4: OFFLINE training with Belux Mentor on Luxembourg Tower (ELLX_TWR)
Step 5: OFFLINE practical assessment on Luxembourg Tower (ELLX_TWR) with Belux Examiner
Step 6: Student 1 rating upgrade (if practical assessment was successful)
>>> …Controller is now allowed to staff ELLX TWR solo
Step 7: Controller will now continue practicing ONLINE until he/she feels ready to proceed to the next step
Step 8: ATSimTest Student 2 rating theory test
Step 9: ONLINE/OFFLINE training with Belux Mentor on Brussels Tower (EBBR_TWR)
Step 10: ONLINE/OFFLINE major endorsement check on Brussels Tower (EBBR_TWR) with Belux Examiner
Step 11: Student 2 rating upgrade + EBBR TWR major endorsement granted (if major endorsement check was successful)
>>> …Controller is now allowed to staff all Brussels FIR TWR (or lower) stations solo
Step 12: Controller will now continue practicing alone ONLINE until he/she feels ready to proceed to the next step
Step 13: ATSimTest Student 3 rating theory test
Step 14: ONLINE/OFFLINE training with Belux Mentor on Luxembourg Approach (ELLX_APP)
Step 15: OFFLINE informal practical assessment* on Luxembourg Approach (ELLX_APP) with Belux Mentor
Step 16: ELLX APP solo endorsement** granted (if informal practical assessment* was successful)
>>> …Controller is now allowed to staff ELLX APP stations solo
Step 17: Controller will now continue practicing alone ONLINE until he/she feels ready to proceed to the next step
Step 18: ONLINE Controller Practical Test (CPT) on Luxembourg Approach (ELLX_APP) with Belux Examiner
Step 19: Student 3 rating upgrade (if CPT was successful)
>>> …Controller is now allowed to staff all Brussels FIR APP (or lower) stations solo, except for EBBR APP
Step 20: ONLINE/OFFLINE training with Belux Mentor on Brussels Arrival (EBBR_APP)
Step 21: ONLINE major endorsement check on Brussels Arrival (EBBR_APP) with Belux Examiner
Step 22: EBBR APP major endorsement granted (if major endorsement check was successful)
>>> …Controller is now allowed to staff all Brussels FIR APP (or lower) stations solo
Step 23: Controller will now continue practicing alone ONLINE until he/she feels ready to proceed to the next step
Step 24: ATSimTest Controller rating theory test
Step 25: ONLINE/OFFLINE training with Belux Mentor on Brussels Control (EBBU_CTR)
Step 26: Controller will now continue practicing OFFLINE (alone or with Belux Mentor) or ONLINE (with Belux Mentor) until he/she feels ready to proceed to the next step
Step 27: ONLINE Controller Practical Test (CPT) on Brussels Control (EBBU_CTR) with Belux Examiner
Step 28: Controller rating upgrade (if CPT was successful)
>>> …Controller now is allowed to staff all Brussels FIR stations solo

For more info on how to become Senior Controller (C3), Instructor (I1) or Senior Instructor (I3) rated, click here

* An informal practical assessment is defined as a training session during which the trainee takes control and demonstrates that he/she is ready for the solo endorsement.
** The ELLX solo endorsement is defined as in, and compliant to, GRP § 4.5.