So sorry to hear about your diagnosis. CIS is a form of transitional cell carcinoma that appears as a rash on the surface of the bladder rather than as a solid tumor (the other form of TCC is sort of like a mushroom that extends into the bladder.) As Antonio said, CIS is always high grade.
I assume from the treatment that has been recommended, that it has spread beyond the bladder lining. IF it is still confined to the bladder lining, then BCG is the usual standard of treatment, as Antonio mentioned. However, if it has spread than radical cystecomy is the usual solution. In your case, if RC is not possible, chemotherapy is the only option.
I would agree with Antonio that a second opinion would be a good idea (you said you didn't want advice, but is IS free!) Continuing with the "advice" I would suggest a second opinion at a center that specilizes in bladder cancer treatment of difficult cases, such as a university or NCI designated cancer center.
Since most patients in your position chose RC's, there may not be many here who have done the regimen you are asking about.
Wishing you all the best
Sara Anne