You can enable interrupts using the ctl_enable_interrupts function call.
int ctl_enable_interrupts(void);
You can disable interrupts using the ctl_disable_interrupts function call.
int ctl_disable_interrupts(void);
These functions return the enabled state of interrupts before the operation which you can pass to ctl_set_interrupts to restore the previous interrupt enabled state.
void ctl_set_interrupts(int e);
Note that you can call a function that causes a task switch with interrupts disabled. The CrossWorks tasking library will ensure that when a task is scheduled that interrupts are enabled.
You can remove a task from the waiting task list using the ctl_task_remove function call.
void ctl_task_remove(CTL_TASK_t *);;
Note that once you have removed a task the only way to re-introduce it to the system is to call ctl_task_run.
You can change the priority of a task using the TaskSetPriority function call.
void ctl_task_set_priority(CTL_TASK_t *, unsigned char priority);
If you want to change the priority of the currently executing task then pass ctl_task_executing as the task parameter.