Well, a while ago, I started a project which was supposed to be a 84+ like clock for the nspire. (With Ndless)
But Lua came, so I gave up.
Here is the code used to display the time :
bufDrawString(buf, 50, 0, "Nspire clock - By Loic Pujet", 0);
uint32_t time = *(volatile uint32_t*) 0x90090000;
sprintf(clock, "%lu : %lu : %lu", (time%86400)/3600, (time%3600)/60, time%60);
bufDrawString(buf, 115, 150, clock, 0);
EDIT : Oops, I haven't seen that this post was quite old.
But maybe it will be useful for someone