Yes, though how it would work in each edition is slightly different.
In RMU, you could quick cast the Long Door spell with as few as 2 Action Points (at a -50 to the SpellCastingRoll), and then you'd have 2 AP left for a melee attack (again, quick, at -50).
If you were hasted, you would have more to spend, and the attack would be at less of a penalty.
And now of course I just realized what forum I was in. In RM2, yes, you can still do it, but only with Haste I believe. I don't think you could normally do both because casting a spell is 75% activity, and melee requires at least 50% activity. Even beyond the activity cost, RM2 would require an Orientation Roll after the Long Door, and a low roll might negate any further action that turn.
Or you can cast Long Door on *someone else* and have *them* attack. In RM2, given how the combat round phases work, I think it is entirely possible, and without penalty, unless you assign a disorientation penalty or require an orientation roll for the spell target, but I don't think (I might be mistaken) it was mandatory in the core RM2 rules: The only mention of Orientation Rolls I could find was in Arms Law section 3.3, where it simply says "when required by the GM". Additionally, making orientation rolls slowed action resolution significantly since it required *two* rolls (the orientation roll, then the roll to see if the character was in control since ORs were resolved as moving manoeuvers). You could simply apply the result of the OR as an action modifier (either as a die roll modifier, or as a % of activity allowed), but once again, this is not canon, rather extrapolation.
Or you can simply rule that disorientation is only for those who are not used to be the target of instant travels - it's bad the first time, but you get better with practice : I would use a -20 default penalty and apply the usual experience modifier (x5 the first time, x2 the second time, x1 for the few times after, and x0.5 when it becomes routine). If you're especially finicky, you can adapt the modifier to the type of magical transport (lower base penalty for Leaving since the target can see the end point, higher base penalty for Teleport as the whole environment is different). But once again, those are not canon in any way.
I for one, used the quick, dirty, and slightly high-fantasy variant: no disorientation when the target can see the end point, and requires the rest of the round to re-orient if the target cannot see the end point, which means that you don't get the benefit of surprise (any opponent will likely have to re-orient as well unless they were actually expecting people to appear suddenly right where they actually do).
