Delphi 6 and Uin64

Delphi 6 and Uin64

How can I do that with Delphi 6? UInt64 is not known in D6. It was
introduced in later versions.
var
i, j: Int64;
if UInt64(i) < UInt64(j) then ...
I am thinking of an asm procedure.
function UInt64CompareLT(i, j: Int64): Boolean;
asm
???
end;
function UInt64CompareGT(i, j: Int64): Boolean;
asm
???
end;