I couldn't find a specific guide on connecting the Intensity to QPST, so here:
How to view the Samsung Intensity's Filesystem:
1. Make sure you have the CDMA drivers installed.
2. Download QPST from the usual places.
3. Turn OFF your phone.
4. Connect your phone to your computer via USB.
5. Wait for the "Battery Charging" icon to appear.
6. Open the QPST EFS Explorer
7. You should see your phone on window that first appears, if you do not, read the guide below.
If you do not see your phone on the list, QPST may not be set up to use the port your phone is located on.
1. Go to your device manager (go to Start>Run> and type devmgmt.msc) and look for "Modem".
2. Expand the "Modem" section and look for 'Samsung Mobile Modem'.
3. Right click it, and choose 'Properties', then choose the 'Modem' tab.
4. The port will be at the top (COM#).
5. Open 'QPST Configuration' and click 'Add New Port'
6. In the box labeled 'Port', enter the COM# you found before, then click OK.
If your phone isn't on the port selected, press F5 (Refresh). If it still isn't there, try using the port one higher than the one Windows gave you. Ex. If the phone is reported on COM4, use COM5. Why this works, I'm not sure, but it was what I had to do for mine.
After you finish the steps above, reopen the QPST EFS Explorer, and your phone's filesystem should be visible, but you WILL NOT be able to edit it in any way (except the pictures folder).
Still looking into a way to edit the filesystem and use MP3 ringtones. Damn you Verizon!