The following application note on the Keil web site discusses how to do this using a timer and an interrupt to generate 1ms delays.

http://www.keil.com/appnotes/docs/apnt_105.asp

If you want shorter periods, you can use the _nop_ inline function to insert a single NOP instruction into your program. So, for example,

_nop_();
_nop_();
_nop_();
_nop_();
_nop_();

Generates a 5-clock delay.

Jon