Simple programming help with the Prime

[Angus]

I tried to program an adoption of dealing with different number bases. Inspired by the hp42c menu.
What I ended up with about stack manipulations is something like the following as a return value:

In a program
(...)
RETURN " 32 4 R→B(3)"; //hex interpretation
(...)

That works. But not really satisfying. Behaviour seems to have changed after the latest patch. I opened a post, but there were no answers. Maybe I will split it up into smaller subposts.

If you enter 123 <enter> and press the user key (actually I'm working on soft-menu hence my request for static softkey assignment) that does the 2hex command you have 123 on the stack and 32 4 R->B(3) on the entry line. So you have to confirm with enter again and it is done.

You can in a way 'put' data on the stack as a string like this. But that is far from RPN entry. :-(
How can you pass the entry line to the parser from a program? Having to press enter is nonsense rpn-wise?