I have an RB2011 hooked up to a SXT Lite5 300m away from another SXT Lite5 in order to get an internet connection. I am unable to Winbox into the RB2011. How can I do this?

Depends on how everything is set. What about romon?

I didn't set romon up.

I also can't be specific about the config because I'd need to pull it from the router... which I can't access.

I am unable to Winbox into the RB2011. How can I do this?

If you've forgotten the RouterOS password it can only be reset by reinstalling the router -
http://wiki.mikrotik.com/wiki/Manual:Reset

If it is just a routing problem you can daisy chain the mac telnet from one device to its neighbouring device and through it to its far distant neighbour...

Get in from where? Note that by default the Eth1 is firewalled on this unit