As long as your receiver lets you know the frequency of each test tone (so you know where to apply the EQ).
Alternately, this site has a tone that starts at 150Hz and slowly decreases the pitch with a digital readout of the frequency. Playing it and watching your SPL meter should give you a pretty good idea of where you have spikes and dips in the FR (as well as determining where useful bass ends...my PC system stops around 49Hz
).
The site also provides test tones at 10Hz intervals, but I'd like to see smaller increments between frequencies since at low frequencies, 20Hz between 20-40Hz represents an entire octave!
http://onlinetonegenerator.com/subwoofer.html