Can you explain how to do it "via audio chain"?
This involves either plugging an external tone generator in to the soundcard, directly or via a mixer, or using an application such as Numorse or one of the plethora of CW commercial, shareware, and freeware offerings. There are plenty of applications that allow a key to be connected to the USB, gameport, or serial connectors on the computer so do plenty of research to find the right one for you.
With the applications virtual sound routing such as VAC and Soundflower can be used so that no additional external hardware or connections would be required.
As with all audio inputs into HamSphere ensure that the levels are such that they are not causing distortion or interference across the band.
There is also a software called cwType that can be used generate a sine tone keyed by the LPT or RS232 port. Simply connect your hand pump to 2 pins in the LPT port. It will require a Centronix connector and a soldering device. The tone can be mixed into the HamSphere transceiver's mic input via the computer audio mixer. The important thing is to keep the audio input low. Max 1 on the ALC scale or it will make your transmitter start splattering on the band.