This would be amazing, how do I work out carrier/miles for this? Obviously in J I would get lounge anyway? Is this through the krisflyer site? I have plenty of VFF miles.
One way BNE-CAI is 78k miles + taxes etc accordingly to the online site. Taxes will vary depending on route/airlines booked, but will be a few hundred. You will need 105,300 VA points to transfer to SQ. Any J redemption will get lounge access.
Do you have a Krisflyer account? If not, create one and link to your velocity account so you're ready to transfer over when you need.
On the SQ site search "Redeem flights" BNE-CAI and it will give you some options, mostly BNE-SIN-BKK-CAI on SQ/SQ/MS, some BNE-SIN-IST-CAI on SQ/TK/MS.
It doesn't seem to come up with BNE-BKK-CAI on TG/MS online, but if you call them they may be able to ticket that route. Check for availability BNE-BKK and BKK-CAI separately so you know what to expect when you call. No guarantees in this game but you can try your luck.
BNE-BKK-CAI will be the quickest route, but BNE-SIN-IST-CAI on SQ/TK/MS should be nicer product most of the way, with just the last short hop on MS. 2 stops will always add significant travel time, so given you are time sensitive, aiming for BNE-BKK-CAI if they will ticket it should be the best for you.
Alternatively, just search for a business reward BNE-CAI on the VA site. EY BNE-AUH-CAI is 121k points +$674.01 (VA charges US$205 per sector for EY redemptions).
Do you have any QF points? If so, look at J and F on EK BNE-DXB-CAI as well.