first consideration: you are hardcoding a value.. to add "force user" directive, just "copy" the ForceGroup lines.. jus use a different variable name and remember to add the value into db
something like
db accounts setprop ibayname ForceUser myuser
then: if you need something, just make a donation to the project or hire someone and pay him..
I know there are many "alternatives" out there, but if you choose SME, you have to know it, understand how it works and do things in "the SME way"
IMHO you don't need to do any kind of howto, but please file a bug (more precisely a NFR), post there the fragment and report here the reference, thank you
finally: SME is a collaborative project and need help to be improved.. if you have time/money to invest in the project, you are welcome