Oh, this takes me back to my university days where I spent time with Lejos [0] on an RCX brick (32 kilobytes of usable space).

I recall using Eclipse for development and I am sure the build process involved uploading the JVM and program code via a USB infrared interface.

Have to say that I preferred using "Not Quite C" [1] due to it having a simpler syntax and intuitive support for cooperative multitasking.

[0] http://www.lejos.org/ [1] http://bricxcc.sourceforge.net/nqc/