My home theater amp has NO line level outputs. The ony option I have are the actual speaker out (which are spitting out 60w!). I know NOT to connect that directly to the beolab line-in's. My question is, will a speaker-to-line-level converter work (the same kind usually used for old car stereos), and if it will still allow me to control the volume of the speakers using the amp's volume control. 

I am aware of attenuated cables, but not many manufacturers produce them, and the pricepoint is less than attractive for me at this point.

Any experience hooking up active speakers to an amp WITHOUT volume controlled line level outs will help!

I would suggest talking to Steve at Sounds heavenly - Beolabs are expensive and I wouldn't risk them for the sake a few pounds of cable. Essentially you will be adding a large resistance to the cable which will reduce the output to line level so it will work.