There are some pretty sweet tones out there uploaded by HD500 users and you can use these and or tweak/convert them in farm if you download POD HD500X Edit
As a tip you can open farm and 500edit at the same time and mimic (as best you can), the FX and the ordering of them + settings.
In 500, all the settings will be in front of you in the interface see below ....so that makes it easy.
Next you need to manually adding them in farm as best you can. There was one FX in this example HD500 tone that literary does not exist in Farm. It was this "colordrive distortion" pedal.
Had to google it, as I never heard of this pedal before....so learned something new I guess.
Anyway, you may have to find a substitution in these cases.
See next image below which is the same tone now in farm (at least a best effort).
If you can match and get the ordering close, this technique may work well for you to get some additional tone by users when you don't own the HD500.