My Trick
The trick I use when I need to get audio into Pro Tools and I am limited by either a lack of sync or I/O, is to do this, take a sound source like a signal generator, or even a click/cowbell type sound. The idea is to get something that makes a sharp transient when it sounds. Round this sound to all 8 tracks of your analog recording and record it a second or two befor the music starts on your 8 track analog recording. Now you can record each of those tracks into Pro Tools, one at a time even.
Then you need to edit them to line up correctly. You can use the use tab-to-transient feature to make a selection right where the transient of the new sound is, on each of the tracks. Then seperate the recorded file into two regions by pressing crtl+e or selecting it from the edit menu. Once this is done, you can deleted the information recorded before the new sound.
Since you recorded the new sound to all 8 tracks at the same time, it is a point of reference, and since we use tab-to-transient to select exactly where the transient begins on each tracks waveform, and then removed the audio occuring before that, each track is starting at the same place now.
Now you can go into grid mode and line them up. Or you can just drag each waveform to the left so they all start at 0.
It sounds tedious, but I have found it is much faster than trying to eyeball or manually line up multiple tracks without a sync reference.
Hope that helps. Let me know if you need more info.