Mick,
For daytime shots, I use the Canon wireless remote; it's also fine for doing 30 second exposure astrophotographs (with mirror lock-up, as well).
For the long exposures, I built myself a serial cable (my first electronics project since high school) and it works perfectly with DSLR Focus.
All the parts were available from D_ick (underscore used to prevent censoring) Smith Electronics.
Click
here for the circuit diagram and photographic reference I used for when building mine.
It took all of ten minutes to build.
I hope this helps.
Regards,
Humayun