I don't have any personal experience with this, but just something for you to be aware of...
When doing a double major, you can only count 2 units towards both majors. You have a total of 16 commerce units to do, of which 6 are core.
Then on top of that, to complete a finance major you need another 7 units (ACC1000 counts towards finance), meaning you've now done 13 and have 3 left. If you cross credit BFC2140 and BFC2340 to the actuary major, you have 6 units left to complete the major. Even if you do etc3460 (which is on the list for both) as part of the finance major, you would still need 6 "actuary" units. So this brings you up 19. So you can't fit it in unfortunately.Even if you could do these 19 units (going over the credit requirement for your course, not usually allowed I don't think) you wouldn't have all the required exemptions for part I accreditation.
Unless you're doing commerce/science, in which case you can do some maths units to count as some the actuarial units which may make it possible. MTH2222, MTH3251, MTH3241 etc.
If you're doing com/law you only have 5 core units so have 1 extra unit to play with, but you still can't fit it in with a conventional path.
But best to speak with a course adviser to see how you go. If you want to major in actuarial studies though, have a look
here to see all the units you need to do in order to get all of the exemptions.