Ouch. Just...no. Don't do it. The whole point in the pool is to manage how to use the suit - because its basically a giant balloon around you. If the BCD hose wont fit, and I don't know any that would reach that far - or have the correct fitting - I'd just wait till the drysuit hose is on your first stage and do it properly.
If you have a regulator set with the alternate air integrated into the low pressure inflator, the lp hose is bigger than standard and will not fit on a dry suit inflator.