set up an enhancement storage unit in your base and set it's permissions so your other toons can access it. that way you can hold 100 enh's in one shot.
I have found a quick work-around for this is to change to dynamic mode, drag the power to a space that would allow for 6 slots, slot the power, then drag it back.
Mid's will show 3 of the 6 slots blackened out as 'impossible' locations but will still allow you to slot enhancements and (from my observation) still count the enhancement stats.