It's also a bad idea to set shortcuts anyway [even if you could do it effectively !] - the user might be angry at you when you overwrite their own shortcuts with yours !
You can instruct the user of your tool how to add their own shortcuts, but don't force them - you are meant to be their friend, not their master.
If you want the user to press certain keys to do certain things in your Tool, then you are pretty much limited to Ctrl, Alt, Shift and Tab, or say numbers 0-9 followed by other characters which can be parsed off from the user's typed text input - so "1:3" can be read in as a slope of "1 in 3", or "1left" gives "left" when leading numerals are stripped off...
All other keys can potentially be already assigned to other tools and actions by the user, so pressing "L" for left is unlikely to work as that will likely invoke the "Line" tool - and it's including key-combos like Ctrl+Shift+V [typically for Edit>PasteInPlace]. So that's kind of use in your Tool is essentially a bad idea...