How do I install the Glide Wrapper on Diablo 2 with PlayOnLinux?

I'm not sure how specifically this applies to Diablo or your patch, but as for adding parameters, two ways come to mind:

1)

1. Click "Configure" in the upper right.
2. Select the appropriate shortcut from the list on the left of the window that appears.
3. Put -3dfx in the "arguments" box on the "General" tab.

2)

1. Click "Configure" in the upper right.
2. Go to the "Miscellaneous" tab.
3. "Open a Shell"
4. Find and launch your executable adding your arguments as desired.

The second method is the one I personally seem to have more success with, but it is a bit harder to initially nail down how exactly to launch your executable.