Data items can be assigned an absolute address with the at
<address> keyword, in addition to a storage class, e.g.:

xdata at 0x7ffe unsigned int chksum;

In the above example the variable chksum will located
at 0x7ffe and 0x7fff of the external ram. The compiler
does not reserve any space for variables declared in
this way (they are implemented with an equate in the
assembler). Thus it is left to the programmer to make
sure there are no overlaps with other variables that
are declared without the absolute address. The
assembler listing file (.lst) and the linker output
files (.rst) and (.map) are good places to look for
such overlaps. Variables with an absolute address are
not initialized.
So thats how you would do it in sdcc i dunno about kiel