I presume it's the same as a normal HB profile.
Load up HB whilst on your farming character. head to a mailbox you wish to use in your farming area, stand directly in front of it.
Hit the profile+meshes tab in HB, press my position, copy what it says in the HB window e.g. <Hotspot X="-9999.999" Y="999.9999" Z="999.9999" />
Open your GB2 profile, find the <Mailboxes></Mailboxes> tags. Paste the lien you copied from the HB log in between the two.
<Mailboxes><Mailbox X="-9999.999" Y="999.9999" Z="999.9999" /></Mailboxes>
Replace Hotspot with Mailbox. Save changes and jobs done.
I PRESUME. I've not made profiles in a fairly long time xD. And of course, the same for a repair vendor but instead you target him and click targets position and stick it between the repair tags without having to change anything....