kaos513,
Feel free to correct me if I am wrong. I have a similar RF generator (Mine is an HP 8657D. Very similar to yours)
There is a BNC jack on the front panel labeled "AM/FM 1 V Peak In/Out". I believe you can use this jack to directly inject an audio tone (1KHz or 400 Hz in my case) into the microphone jack to "peak" the transmit of your radio (though I have never used mine this way) or you can supply an audio tone from an external audio tone generator (of any audio tone you wish) into this jack that will be mixed with the RF output to peak the receiver section of your radio. (using the "Ext" button on the front panel of the RF Signal Generator)
Most alignment instructions state to "inject a 27.185Mhz, 1000Hz (or 1Khz) @ 30% modulation" (or something very similar) to peak the receiver section. Using the RF OUTPUT jack on the Signal Generator and pressing the "Int" button on the left side of the front panel that is connected to the antenna connector of your transceiver.
Using the supplied BNC jack on the front of your RF signal generator, you could use an external Audio Signal Generator and inject an 800Hz or 300Hz or 199Hz or whatever tone you wish into the RF Signal Generator that will then be mixed with the RF signal output to align the receiver section.
Personally, I use the standard 1Khz tone the signal generator supplies for receiver alignment as it provides a "comfortable tone" for my ears to focus on while peaking the various coils. I also have a separate audio signal generator that will inject a single tone or a two tone input into the microphone for transmitter alignment.
I hope this helps.
73
David