Probably not. I haven't worked with that Wacom, but I've attempted to use a few similar products from Topaz. These small signature pads don't work by emulating a mouse, but rather by capturing the signature in either an image file format, or a proprietary signature format (which contains some biometric information like stroke timing and pressure in addition to the picture of the signature).

Now if you had a larger "drawing tablet" style wacom (or something like it) that essentially emulates a mouse input for the whole screen, THAT would work with the signature fields out of the box.

It may also be possible to write some custom integration, but that would take a bit of work. I see that there are free and paid versions of an SDK for the STU-300. But this integration would probably not work with the signature field, rather you would have to interact with a custom HTML field and use some javascript to ensure the image gets saved properly similar to how the old signature solution worked (from the BPM251 demos).