Having trouble getting helpfiles to work

1) How do we specify VBProject.Helpfile to point to the same folder as the
installed addin?
We have tried:
VBProject.Helpfile = ThisWorkbook.Path & "\MyHelp.chm"

but we get VBA access not trusted error (424 object required), If I allow
trusted acces to VBA it's goes thru however , I have to tell all my useres
to allow VBA trusted access in Macros Security.

2) ThisWorkbook.VBProject.Helpfile returns ???? until I set it locally using
the Project properties, this occurs when moving the xla from one machine to
another, on the first machine it is set to "MyHelp.chm", but when i try and
read it on another machine it retruns ????.

we need this so when the user hits F1 on a VBA userform, it pulls up the
right help file. also when the function wizard displays "get help of this
functions" to point to our helpfile. I think we can get round the function
wizard with application.MacroOptions, but not F1 on Userforms.