Cathay Pacific Asia Miles - OLCI for connecting flights

I'm flying HKG-BKK-DEL on CX713/CX751 on the same day (just transit in BKK, will get both BP in HKG), and I'm wondering how does OLCI work for this case?

Since I'm not taking the nonstop flight due to timing issues, I figure I may as well leave a bit earlier and get the extra 553 Club Miles by flying on two sectors with separate boarding passes instead of CX751 all the way from HKG-DEL, where I'd only get miles for the straight line distance between HKG-DEL.

CX713 leaves HKG at 8:55am. Can I log in at 8:55am 2 days before the flight and do online check in for both sectors?

I've never attempted OLCI before for a connecting flight before and not sure how it works.

(Ordinarily I wouldn't attempt this silliness for such a small amount of miles, but the extra 553 Club Miles I get from connecting onto a different flight number will put me at exactly 60,041 Club Miles along with other trips I have planned).

Not sure, but don't think it will work.
Indeed doing HKG-BKK-DEL on the same flight will give you the miles for the direct connection HKG-DEL.

I'm flying HKG-BKK-DEL on CX713/CX751 on the same day (just transit in BKK, will get both BP in HKG), and I'm wondering how does OLCI work for this case?

Since I'm not taking the nonstop flight due to timing issues, I figure I may as well leave a bit earlier and get the extra 553 Club Miles by flying on two sectors with separate boarding passes instead of CX751 all the way from HKG-DEL, where I'd only get miles for the straight line distance between HKG-DEL.

CX713 leaves HKG at 8:55am. Can I log in at 8:55am 2 days before the flight and do online check in for both sectors?

I've never attempted OLCI before for a connecting flight before and not sure how it works.

(Ordinarily I wouldn't attempt this silliness for such a small amount of miles, but the extra 553 Club Miles I get from connecting onto a different flight number will put me at exactly 60,041 Club Miles along with other trips I have planned).

You can only do OLCI for a specific flight 48 hours before it departs. So no, you can only check in for 713 at 8:55, then you can check in for 751 48 hours before its scheduled departure from BKK. If, however, you were on 751 all the way HKG-BKK-DEL, you would be able to do OLCI for both sectors since it is theoretically one flight (as the mileage situation indicates).

I suppose you could also do OLCI for your connecting flight at the same time as your flight sector. I've done that for LH, so I would think that CX IT should have similar capabilities.

The CX website indicates (although it does not address your question directly):
5. Can I also check in for connecting flights with other airlines?

Yes, where possible, you can check in for connecting flights with other airlines as long as the first sector is Cathay Pacific or Dragonair. Please note these check-ins are subject to other airline policies and restrictions

I suppose you could also do OLCI for your connecting flight at the same time as your flight sector. I've done that for LH, so I would think that CX IT should have similar capabilities.

No, you can only check-in a CX or KA FLT 48 hrs before its schedule departure time. However, you might be able to OLCI for a connecting FLT not operated by CX / KA as it would pop-up at the same time as your last CX / KA FLT does. I, however, can rarely succesfully OLCI non-CX / KA connecting FLTs.