I have a Yaesu FT-60, and it can transmit on 2m, 70cm, and receive 1.25m and 33cm bands. I would really like to find a way to get it to transmit on 1.25 and 33cm. Is there a way to make this happen?
No. You likely would need to build two new transmit stages and rewrite the firmware. Each transmit stage uses a precise final oscillator and mixer which is specific to the frequency band as well as a filter to suppress harmonics, use of the hardware for 70cm at a 33cm frequency would result in most of your transmit signal being filtered out - if it was even possible.
There are quad-band transmitters - yaesu makes a few - I am not aware of any with 33cm coverage, however. This would likely be a simple mod in a desk unit, but any modification of this sort of a handheld or even mobile radio is extremely difficult due to the fact that so many functions are concealed inside multi-purpose chips, many signals are inaccessible due to multi-layer PCBs and components without exposed leads, and there is simply no room inside the case for any add-on boards that we could manufacture.