The SLT-A99V is supported by LR from version 4.2.
You do need ACR 7.2 or later for that camera, however PSE 10 only supports up to ACR 6.7 and not ACR 7.2.
Since you have LR, the best approach would be to use LR to convert the RAW to a TIF and import that into PSE 10.
Alternatively, you could download the latest DNG converter and use that to convert the RAW files to DNG files and then import the DNGs.
Out of interest, if you use LR, why do you want to import them into PSE? I use LR as my organizer and only use the PSE editor as an external editor when I want to do more complex editting - I don't need the PSE organizer.