I have done this and you only need to spend 12 hours acclimating your mollies. You can use a drip system that will drip saltwater in their water. There are calculations on the web if you do a search to calculate the drip rate. You can also add small amounts of SW every 10-15 minuets. Check the SG and make sure you do not exceed .002 increase every hour. You want to go from 1.000 to 1.023-1.025 over the course of 12 hours.
That's good to know. I use the drip method to acclimate all of my fish anyway. I will probably take a longer time with the Molly since she'll be in the QT tank for a while anyway. Thanks for the info!