Any sort of abrasive etching works great. Diamonds, silicon carbide, aluminum oxide in a sandblaster, flat lap, stained glass grinder, dremel, whatever.
Acid, in general does not work. Some formulas work, sort of, but one of borosilicate's advantages (for chem labs) is resistance to acids and corrosion in general. I've heard people say this or that works, I've never succeeded at getting acid to do more than vaguely dull the surface.
There are lots of options for sand blasters. Mainly you're deciding between a pressure pot and a siphon system (which are, respectively, expensive and cheap). Either one blasts abrasive at the glass and works fine. Pressure pots are nicer but it might not matter unless you're carving a lot.
Tumblers are great. There's a vast amount of tumbling media and goodies out there... check out sites like
http://www.kingsleynorth.com to see the vast range of lapidary equipment from which you can select. All of that works great on boro, because as far as lapidary is concerned, it's just a medium hard stone similar to quartz.