Yes, you could input a bass and record ideas from it into your Spider Jam amp. You might not want to run Amp Modelling (then again, maybe you do!).
The only thing I can think of that you might need to be careful with might be if you have active pickups on your bass... just be aware that lower frequencies/transients might "clip" the input circuit and manifest itself as a digital peak/overload sound in the recording if you're not careful with monitoring the input signal of active electronic instruments.
But other than that, yeah... you should be fine!
To use the BASS1 and BASS2 you will need to connect the bass to AUX input located on the front of amp to the left of the Guitar input. I would suggest to try and roll off the bass on your bass guitar if possible, so that you do not overload and damage the speaker with excessive low end.