Well elemantary you can not. Tachnically its possible but thet would mean youd have to parse the maya file somewhere wich would pretty much be the same as loading the file.
So while it might be faster, it may not be faster for years once you account the dev time into this. So say it takes your undivded attention for the next 3 months thats 3*4*80 = 480 hours. Now say that the average opening time your talking about is 10 minutes and you could cut that to 1/10 then that means you saved 9 minutes each open that means you need to open 3200 times to recoup your investment. So say you have a team of 10 persons who each use this every day once on the average taht would mean your investemnt would pay itself back in one year 3 months (3 months for dev time). Now this calculation is VERY optimistic indeed so id say you actually only gain 1/5 of the time at most and would need to work on the tool much more once you account for bugfixes. So unless you have a customer base in the hunderds then its not necceserily worth it.
It would be better to presure autodesk to have this feature.
I know its possible in batch mode.
No its not, even in batch mode you open the scene.
Is there any time-saving way?
Not really. Not in hindsight but if you have this requirement up front then you could use a exterenal file to store just that data.