The units of the intercept are the same
as those of the response. As I understand
it, you can restate in other units exactly
as convenience or whim dictates. No
statistical issue arises.
I think what Cordula really wants might be centring, rather than scaling.
If you extract a constant X_0 from an X-variate before fitting the
regression model, and therefore regress Y with respect to X-X_0, then the
intercept will be the expected value of Y if X==X_0, instead of the
expected value of Y if X==0. This often causes the intercept to make more
sense, although, as Nick says, the intercept is still expressed in Y-units.
