Ok gents, the full guide has been posted on EAs forum.
To me it seems as if it has all been overcomplicated in it's description. Here's what I understand to be the basic necessary info.

Links = league/club/nation connections between players. Lines = the connections between positions in the formation.

Bonuses come from manager, +1 (league OR nation link, the bonuses do not stack up) and Loyalty +1 (after 10 games).

Full chem + no bonuses is 9.

To reach 9 chem without bonuses you need an equal or slightly greater number of links to the player than the number of lines going into the position.

To reach 10 chem without bonuses you need 1.6x the number of links to lines.

Nation = 1.
League = 1.
Club = 1.

Further complications arise from wrong position but we're all used to that. If you want 10 chem on a player, you need to follow the old formula of links to lines, with the new numerical value on links, and the +1 bonus from the manager or loyalty.
If you have a player on 9 with no dead links it's because his total link 'value' is less than 1.6 x the positions lines. League or nation manager bonus will bring him to 10.

This actually simplifies things a little because with the manager + loyalty bonus of +2, you can now bring a related position/insufficiently linked player from 8 chem to 10 by applying them both rather than relying on double links like in the old system.

Here is the full guide, should you wish to melt your brain.
http://forum.ea.com/uk/posts/list/2595535.page

Following table might still be of some use to people.

What is the Effect on Chemistry When Placing a Player Out of Position? 
Players can be placed out of position, but this will impact the player's Individual Chemistry. The table below lists the maximum chemistry each player position (in GREEN) can achieve when out of position. RED represents the Individual Chemistry value without bonuses applied. BLUE represents the Individual Chemistry value with both bonuses applied.