Ok, I've done some testing and here's what I've found. Note: I'm using SPB Mobile v3.1
You can use voice recording during any call, by going in to 'Notes' while you are on the call. Once you are in Notes, you should see a record button in the bottom left corner. If not, you can enable to it by clicking Menu | View Recording Tool Bar. Click the red button to start recording. You stop recording by closing the Notes.
Without this utility, you will only hear your own voice, maybe you'll hear the other person but it will be faint. So installing this utility makes yourself and the other person sound very clear. Recording of phone calls should be available on the TD2 out of the box even without this utility, but this utility makes both voices sound clear.
The other question was about storing the recording on the SD card. To set this, click on Start | Notes. Once you are in Notes, click on Menu | Options and set the 'Save to' to be Storage Card. This should now save recordings to Storage Card\Calls. Nake sure you leave 'Record button action:' set to 'Switch to Notes' or you'll run into troubles where you cant get Notes to open any more.
One last thing... if you dont see 'Notes' in the Start menu, you can enable it by going Start | Settings | Menus and enabling Notes there.
This is how I've got things working, hopefully that helps some others out there. If you know of a better way of doing things, or maybe this utility works better outside of SPB Mobile, please post your findings.
Cheers,
D.