Your options are:
If you mix roles in the same work day?
e.g. Do my other job in the morning and drive in the evening
You must log your 'other job' as OTHER DUTY entries and ensure you take the required REST BREAK.
If you mix roles on different days of the week?
e.g. Do my other job Monday to Wednesday and drive Thursday through to Saturday
You can add a comment of the days you work when starting your Shift on Thursday
e.g. Worked Monday, Tuesday & Wednesday 8 hours each = 24 hrs
You then log your Driving work-time as normal (link) but you must ensure that your Work-time balance does not exceed the 70hrs total -> a starting balance of 46hrs which you must manage yourself.