As BEage has said, you've got the requirements wrong, and you probably already have the required hours.
However, to answer your question about how to log the time, there are two options. As you have no doubt already discovered, the requirements for teaching instrument flying (whether as an FI teaching IMC or IR, or as standalone IRI) are all expressed in terms of IFR hours, with an alternative of "hours by sole reference to instruments" where one hour by sole reference to instruments counts as 4 hours IFR.
So, option 1 is that you log time by sole reference to instruments. This is simple: if you are in a cloud or under foggles, you are flying by sole reference to instruments. As an instructor, you will obviously not be under foggles, so therefore the only time you can log is when you are in a cloud.
Option 2 is that you log your IFR time, and this is more wooly because you can be IFR just about any time you want to be, so long as you comply with the relevant rules (e.g. 1000' rule, quadrantal rule).
To keep in the spirit of the rule, I log my time as follows: if I arrange my flight in such a way that I am prepared to enter IMC if I happen to encounter IMC, then I log it as IFR. This would include a route from A to B where navigation is soley by instruments and I am happy to enter IMC; it would include any instrument approaches or procedural work whilst teaching for the IMC rating; and it definitely includes any time I am actually in IMC.
If I arrange the flight in such a way as to maintain VMC, then I do not log it as IFR. An example would be teaching partial panel - I will not do partial panel in IMC if I can not see an attitude indicator, therefore I always ensure that I maintain VMC when doing these exercises, and do not log them as IFR.
Nothing wrong with having a flight which is part IFR and part not - for example, a partial panel exercise followed by an instrument approach.
That's my personal take on things, and I think it is within the spirit of the law as well as the letter of the law, but it is open to interpretation. A couple of interpretations which are different to mine, for example: one or two PPRuNers insist that an instructor can not log IFR time if he is not at the controls, but I don't agree with this. Also, all night flying in the UK (unless Special VFR inside a control zone) must be IFR, and according to the letter of the law could (maybe even should) count as IFR flight, but I don't believe that it is within the spirit of the law to log this as IFR flight if you are clearly flying and navigating visually for the entire flight. But, at the end of the day, with the exception of the IRI requirements, you have pretty much met the hours requirements to teach for a rating as soon as you have that rating, so it's all pretty academic because no one else really cares.
FFF
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