Just so you know there is also a new block in the new version 3.6. Which allows products to be added simply by entering the code number via the store front.
As an alternative to what Nathan suggests above you could use the above block or even the web front end. The reason I say this is the call centre is poor when products have options etc
We have actually set up an ADDITIONAL site just for processing phone and post orders. This is quite easy using the multisite feature. We have customised the second site so that certain options work differently than our main site.
e.g an extra payment method which does not send an email + also we have made email an optional field not a required one. We also have the second site to have the minimum order at zero (unlike our other site). This allows us to place orders for any amount and also we can delete item/s from a clients 1st order via admin and then place a second order for just a few items. In effect acting as an order editor should a client ammend an order. We the make a manual card payment or refund to settle the difference either way. Then we reprint the paperwork for both orders
Its a workaround but it works.
I hope the next release (or even this one) has an improved order editor and call centre. But I think we have been here before
