Nope ACDSee won't recognize the PHOTO-PAINT format.

Do each one individually, I'd suggest. That way, you can specify the compression and smoothing factors to maximize your quality and compression. That will vary, depending on the values and colours of your pics. It'll take some time, agreed, but it's the best way. You can also resample each to your desired d.p.i. (whether you plan to print them or just display them on screen only.