You can extract the Symantec TOTP secret and use normal apps with it. This guide is from a reddit comment and I revised it slightly:

1. install pre-reqs: sudo pip install python-vipaccess && brew install qrencode

2. Run: vipaccess provision -p -t VSMT

This will print out all the information needed. Note the Symantec ID (it looks like VSMT12345678). It is what goes in the "Credential ID" field when adding a new device on Schwab's website.

3. Save the otpauth://... data into data.txt.

4. (Optional) Modify the issue=Symantec parameter to read issue= Charles%20Schwab Also change VIP%20Access:VSMT123456789 to your Schwab online banking username. These are purely aesthetic changes and will only make a difference in the label that shows up in the Google Auth app.

5. Run: qrencode -o qr.png -s 15 < data.txt to generate the QR image (qr.png) from your otpauth data file.

6. Scan qr.png with your TOTP app.

7. Go to Schwab -> Service -> Security Center -> Manage Two-Step Verification -> Add another Security Token and input the Symantec ID from step 3 (it looks like VSMT12345678) and the current rolling TOTP code from your TOTP.