The North End of Cathedral is located basically at the entrance to the auto road to the left of the highway gate. Most of the routes there can be top roped. However, I would probably caution against the idea at this time of year. It's a very sketchy approach to the top even in good weather. Depending on your skill level, there a couple of routes that you can rap down from the top and climb (in front of observation area). This too has it challenges both technical and otherwise. For starters, it's unsafe and in poor style to top rope anything that someone may be climbing below you (imagine being a leader and getting bopped in the head by someone's errant top rope).
The North End is your best bet to my knowledge. If you must climb now I would recomend leading Child's Play or Kiddie Crack rather than trying to negotiate the approach path. Have fun.