How to charge lithium-titanate battery with lower voltage
I also have some tiny 50mAh LTO cells. Perhaps the same ones? 
I got mine at Battery Space . . . 

http://www.batteryspace.com/LTO-1020-Rechargeable-Cell-2.4V-50-mAh-2.0A-rated-0.12Wh.aspx

They have larger LTO cells as well. Some are offered pre-wired into 5 cell packs 
(nominal 12V) and the charger they offer for these is a basic flood lead acid 
car battery charger, with instructions to unplug as soon as the LED indicates 
full charge (ie: don't trickle charge your lithium batteries.) No BMS in these packs either. It's a kind of crude solution to the problem, but LTOs are, apparently, rather good at self leveling in these 5 cell configurations and 
a lead acid charger happens to be constant voltage/current, proper voltage, 
and only lacking automatic cutoff. 

But, yes, what about just one cell and at a smaller amperage rating? 

This is an ideal solution for that . . . 

http://www.prodctodc.com/5a-constant-current-led-driver-lithiumion-battery-charger-digital-ampvolt-mete-p-428.html#.VUzYTdNVhBc

I actually found the two I own from a Chinese eBay vendor (he might be the original manufacturer,) but it's nice to find them generally available on 
a US-based web site. 

Two tiny set screws allow you to dial in the specific voltage and amperage settings and the multi-colored LED on the bottom board indicate when 
charging is complete (although I'm not 100% sure if the charger automatically 
cuts off at this point.) In any event, this is the answer to your (and my) problem. It will not only charger LTOs, but anything else you can think of in regards to single cell lithium . . . even ones that haven't been invented yet (which will, invariably, come in different voltages than what we have now.) 

Have fun!